OBD2 DIAGNOSTIC OPERATIONAL MODES

The OBD2 system is comprised of nine diagnostic operational modes, each of which supports retrieval of a specific set of diagnostic information. The nine diagnostic modes are:

MODE 1 每 Powertrain Diagnostic Data

MODE 2 每 Powertrain Freeze Frame Data

MODE 3 每 Emission-related Diagnostic Trouble Codes (DTCs)

MODE 4 每 Clear / Reset Emission-related Diagnostic Information

MODE 5 每 Oxygen Sensor Test Results

MODE 6 每Non-continuous Test Results

MODE 7 每 Continuous Monitors Test Results

MODE 8 每 Control of On-board Tests and Devices

MODE 9 每 Vehicle Information


MODE 1 每 Powertrain Diagnostic Data

In OBD2 systems, the vehicle*s on-board computer receives status information generated by the various vehicle sensors, switches and actuators located throughout the vehicle. This information includes values (volts, rpm, temperature, speed etc.) and system status information (open loop, closed loop, fuel system status, etc.).

MODE 1, Powertrain Diagnostic Data, retrieves "real time" signal values (also called §Live Data§) generated by the sensors, actuators, switches and/or vehicle system status information used by the vehicle's computer when calculating and conducting system adjustments and corrections.

The real time vehicle operating information for each sensor, actuator, switch, etc. is called Parameter Identification (PID) Data. Each PID (sensor, actuator switch, status, etc.) has a set of operating characteristics and features (parameters) that serve to identify it. These ※default§ values are also retrieved through MODE 1.

(NOTE) The data retrieved is "real每time" Live Data. The values (volts, rpm, temperature, vehicle speed, system status etc) for the various PIDS may change as the vehicle's operating conditions change. Depending on the specific PID, data may show an actual value returned from a single device (snsor, actuator, switch, etc.), or may show a calculated value based on the inputs from multiple devices.


Sampling Rate

The rate at which PIDs are sampled (the rate at which data is refreshed) varies, depending on the communication protocol used by the specific vehicle (see COMMUNICATION PROTOCOLS for more information). The powertrain PID sampling rates for each communication protocol are:

SAE J1850 (VPW 10.4K), SAE J1850 (PWM 41.6K) 每 150ms per PID

ISO 9141-2, ISO 14230-4 KW 2000 每 90ms per PID

ISO 15765 CAN 每 50ms per PID

(NOTE) Actual refresh rate when viewing Live Data is cumulative, and depends on the number of PIDs selected for viewing at a given time. The greater the number of PIDs selected for display, the slower the refresh rate.


MODE 1 PIDs

(NOTE) Not all PIDs are supported by all vehicles.

PID 00 每 PIDs supported by the ECU

PID 01 每 DTCs, MIL Status and Monitor Status

PID 03 每 Fuel System Status

PID 04 每 Calculated Load Value

PID 05 每 Engine Coolant Temperature

PID 06 每 STFT Bank 1, Bank 3

PID 07 每 LTFT Bank 1, Bank 3

PID 08 每 STFT Bank 2, Bank 4

PID 09 每 LTFT Bank 2, Bank 4

PID 0A 每 Fuel Pressure (Gauge)

PID 0B 每 Intake Manifold Absolute Pressure

PID 0C 每 Engine RPM

PID 0D 每 Vehicle Speed Sensor

PID 0E 每 Ignition Timing Advance for #1 Cylinder

PID 0F 每 Intake Air Temperature

PID 10 每 Air Flow Rate from Mass Airflow Sensor (MAF)

PID 11 每 Absolute Throttle Position

PID 12 每 Commanded Secondary Air Status

PID 13 每 Oxygen Sensor Location

PID 14 每 Oxygen Sensor 1 Bank 1

PID 15 每 Oxygen Sensor 2 Bank 1

PID 16 每 Oxygen Sensor 3 Bank 1

PID 17 每 Oxygen Sensor 4 Bank 1

PID 18 每 Oxygen Sensor 1 Bank 2

PID 19 每 Oxygen Sensor 2 Bank 2

PID 1A 每 Oxygen Sensor 3 Bank 2

PID 1B 每 Oxygen Sensor 4 Bank 2

PID 1C 每 OBD2 Support Requirements

PID 1E 每 Power Take Off (PTO) Status

PID 1F 每 Time Since Engine Start

PID 21 每 Distance Traveled While MIL is Activated

PID 22 每 Fuel Rail Pressure Relative to Vacuum

PID 23 每 Fuel Rail Pressure

PID 2C 每 Commanded EGR

PID 2D 每 EGR Error

PID 2E 每 Commanded Evaporative Purge

PID 2F 每 Fuel Level Input

PID 30 每 Number of Warm-ups Since DTCs Cleared

PID 31 每 Distance Since DTCs Cleared

PID 32 每 EVAP System Vapor Pressure

PID 33 每 Barometric Pressure

PID 3C 每 Catalyst Temperature Bank 1 Sensor 1

PID 3D 每 Catalyst Temperature Bank 2 Sensor 1

PID 3E 每 Catalyst Temperature Bank 1 Sensor 2

PID 3F 每 Catalyst Temperature Bank 2 Sensor 2

PID 41 每 Monitor Status this Driving Cycle

PID 42 每 Control Module Voltage

PID 43 每 Absolute Load Value

PID 44 每 Commanded Equivalence Ratio

PID 45 每 Relative Throttle Position

PID 46 每 Ambient Air Temperature

PID 49 每 Accelerator Pedal Position D (PID 49)

PID 4A 每 Accelerator Pedal Position E (PID 4A)

PID 4B 每 Accelerator Pedal Position F (PID 4B)

PID 4C 每 Commanded Throttle Actuator Control

PID 4D 每 Minutes Run by the Engine While MIL Activated

PID 4E 每 Time Since DTCs Cleared


PID 03 每 Fuel System Status

Provides an indication of current fuel system status (closed loop, open loop, etc.)

Possible values for PID 04 are:

PID Description

Unit

Value

Fuel System 1 Status

-

OL

Fuel System 1 Status

-

CL

Fuel System 1 Status

-

OL-Drive

Fuel System 1 Status

-

OL-Fault

Fuel System 1 Status

-

CL-Fault

Fuel System 2 Status

-

OL

Fuel System 2 Status

-

CL

Fuel System 2 Status

-

OL-Drive

Fuel System 2 Status

-

OL-Fault

Fuel System 2 Status

-

CL-Fault


PID 04 每 Calculated Load Value

Provides a calculated value indicating the percent of engine capacity that is currently being used, derived as the ratio of current airflow divided by peak airflow (altitude corrected).

Possible values for PID 04 are:

PID Description

Unit

Value

Calculated LOAD Value

%

XXX.X


PID 05 每 Engine Coolant Temperature

Provides a calculated value indicating current temperature of the engine coolant.

Possible values for PID 05 are:

PID Description

Unit

Value

Engine Coolant Temp

*C / *F

XXX / XXX


PID 06 每 STFT Bank 1, Bank 3

Provides an indication, as a percentage, of short term fuel trim (STFT) adjustments made to the base fuel trim program, based on input(s) from the vehicle*s oxygen sensor(s). Positive numbers represent increased fuel delivery; negative numbers represent decreased fuel delivery.

Possible values for PID 06 are:

PID Description

Unit

Value

Short Term Fuel Trim-Bank 1

%

XXX.X

Bank 1 - Sensor 1

%

XXX.X

Bank 1 - Sensor 2

%

XXX.X

Bank 1 - Sensor 3

%

XXX.X

Bank 1 - Sensor 4

%

XXX.X

Short Term Fuel Trim-Bank 3

%

XXX.X


PID 07 每 LTFT Bank 1

Provides an indication, as a percentage, of long term fuel trim (LTFT) adjustments made to the base fuel trim program, based on the average of STFT fuel adjustments. Positive numbers represent increased fuel delivery; negative numbers represent decreased fuel delivery.

Possible values for PID 07 are:

PID Description

Unit

Value

Long Term Fuel Trim-Bank 1

%

XXX.X

Long Term Fuel Trim-Bank 3

%

XXX.X


PID 08 每 STFT Bank 2, Bank 4

Provides an indication, as a percentage, of short term fuel trim (STFT) adjustments made to the base fuel trim program, based on input(s) from the vehicle*s oxygen sensor(s). Positive numbers represent increased fuel delivery; negative numbers represent decreased fuel delivery.

Possible values for PID 08 are:

PID Description

Unit

Value

Short Term Fuel Trim-Bank 2

%

XXX.X

Bank 2 - Sensor 1

%

XXX.X

Bank 2 - Sensor 2

%

XXX.X

Bank 2 - Sensor 3

%

XXX.X

Bank 2 - Sensor 4

%

XXX.X

Short Term Fuel Trim-Bank 4

%

XXX.X


PID 09 每 LTFT Bank 2, Bank 4

Provides an indication, as a percentage, of long term fuel trim (LTFT) adjustments made to the base fuel trim program, based on the average of STFT fuel adjustments. Positive numbers represent increased fuel delivery; negative numbers represent decreased fuel delivery.

Possible values for PID 09 are:

PID Description

Unit

Value

Long Term Fuel Trim-Bank 2

%

XXX.X

Long Term Fuel Trim-Bank 4

%

XXX.X


PID 0A 每 Fuel Rail Pressure (Gauge)

Provides a calculated value indicating current fuel rail pressure.

Possible values for PID 0A are:

PID Description

Unit

Value

Fuel Rail Pressure

kPa /PSI

XXX / XX.X


PID 0B 每 Intake Manifold Absolute Pressure

Provides a calculated value indicating current intake manifold absolute pressure (as either pressure or vacuum).

Possible values for PID 0B are:

PID Description

Unit

Value

Intake Manifold Absolute Pressure

kPa /PSI

XXX / XX.X


PID 0C 每 Engine RPM

Provides a calculated value (derived from either an analog or digital input signal) indicating current engine operating speed in revolutions per-minute.

Possible values for PID 0C are:

PID Description

Unit

Value

Engine RPM

rpm

XXXXX


PID 0D 每 Vehicle Speed Sensor

Provides a calculated value indicating the speed at which the vehicle is currently traveling.

Possible values for PID 0D are:

PID Description

Unit

Value

Vehicle Speed Sensor

km/h / mph

XXX / XXX


PID 0E 每 Ignition Timing Advance for #1 Cylinder

Provides an indication of the amount of advance the vehicle*s on-board computer is applying to the #1 cylinder. This value does not include mechanical advance.

Possible values for PID 0E are:

PID Description

Unit

Value

Ignition Timing Advance #1 Cylinder

deg

XX


PID 0F 每 Intake Air Temperature

Provides a calculated value indicating current intake air temperature.

Possible values for PID 0F are:

PID Description

Unit

Value

Intake Air Temperature

*C / *F

XXX / XXX


PID 10 每 Air Flow Rate from Mass Airflow Sensor (MAF)

Provides a calculated value representing airflow rate through the Mass Airflow Air Flow Sensor; typically low at idle to high at wide open throttle.

Possible values for PID 10 are:

PID Description

Unit

Value

Air Flow Rate from Mass Air Flow Sensor

g/s; lb/min

XXX.XX / XXXX.X


PID 11 每 Absolute Throttle Position

Provides a representation of current throttle position (throttle opening) as a percentage. The value may be displayed as either a ※low-to-high§ percentage (1% at closed throttle, 95% at wide open throttle) or as a ※high-to-low§ percentage (high at idle, low at wide open throttle)

Possible values for PID 11 are:

PID Description

Unit

Value

Absolute Throttle Position

%

XXX.X


PID 12 每 Commanded Secondary Air Status

Provides an indication of the current operating status of the secondary air system.

Possible values for PID 12 are:

PID Description

Unit

Value

Commanded Secondary Air Status

-

UPS

Commanded Secondary Air Status

-

DNS

Commanded Secondary Air Status

-

OFF


PID 13 每 Oxygen Sensor Location

Provides an indication of the location of the vehicle*s oxygen sensor(s) (see Oxygen Sensor Designations for more information).

Possible values for PID 13 are:

PID Description

Unit

Value

Oxygen Sensor, Bank 1, Sensor 1

-

O2S11

Oxygen Sensor, Bank 1, Sensor 2

-

O2S12

Oxygen Sensor, Bank 1, Sensor 3

-

O2S13

Oxygen Sensor, Bank 1, Sensor 4

-

O2S14

Oxygen Sensor, Bank 2, Sensor 1

-

O2S21

Oxygen Sensor, Bank 2, Sensor 1

-

O2S22

Oxygen Sensor, Bank 2, Sensor 3

-

O2S23

Oxygen Sensor, Bank 2, Sensor 4

-

O2S24


PID 14 每 Oxygen Sensor 1 Bank 1

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 14 are:

PID Description

Unit

Value

Sensor 1 - Bank 1

V

X.XXX

Sensor 1 - Bank 1 O2S Current

mA

X.XXX

Sensor 1 - Bank 1 O2S Voltage

V

X.XXX


PID 15 每 Oxygen Sensor 2 Bank 1

Provides an indication of the operating voltage or current for Oxygen Sensor 2 Bank 1.

Possible values for PID 15 are:

PID Description

Unit

Value

Sensor 2 - Bank 1

V

X.XXX

Sensor 2 - Bank 1 O2S Current

mA

X.XXX

Sensor 2 - Bank 1 O2S Voltage

V

X.XXX


PID 16 每 Oxygen Sensor 1 Bank 2

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 16 are:

PID Description

Unit

Value

Sensor 1 - Bank 2

V

X.XXX

Sensor 1 - Bank 2 O2S Current

mA

X.XXX

Sensor 1 - Bank 2 O2S Voltage

V

X.XXX


PID 17 每 Oxygen Sensor 2 Bank 2

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 17 are:

PID Description

Unit

Value

Sensor 2 - Bank 2

V

X.XXX

Sensor 2 - Bank 2 O2S Current

mA

X.XXX

Sensor 2 - Bank 2 O2S Voltage

V

X.XXX


PID 18 每 Oxygen Sensor 1 Bank 3

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 18 are:

PID Description

Unit

Value

Sensor 1 - Bank 3

V

X.XXX

Sensor 1 - Bank 3 O2S Current

mA

X.XXX

Sensor 1 - Bank 3 O2S Voltage

V

X.XXX


PID 19 每 Oxygen Sensor 2 Bank 3

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 19 are:

PID Description

Unit

Value

Sensor 2 - Bank 3

V

X.XXX

Sensor 2 - Bank 3 O2S Current

mA

X.XXX

Sensor 2 - Bank 3 O2S Voltage

V

X.XXX


PID 1A 每 Oxygen Sensor 1 Bank 4

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 1A are:

PID Description

Unit

Value

Sensor 1 - Bank 4

V

X.XXX

Sensor 1 - Bank 4 O2S Current

mA

X.XXX

Sensor 1 - Bank 4 O2S Voltage

V

X.XXX


PID 1B 每 Oxygen Sensor 2 Bank 4

Provides an indication of the operating voltage or current for Oxygen Sensor 1 Bank 1.

Possible values for PID 1B are:

PID Description

Unit

Value

Sensor 2 - Bank 4

V

X.XXX

Sensor 2 - Bank 4 O2S Current

mA

X.XXX

Sensor 2 - Bank 4 O2S Voltage

V

X.XXX


PID 1C 每 OBD2 Support Requirement

Provides an indication of the OBD systems/types supported by the vehicles on-board computer.

Possible values for PID 1C are:

PID Description

Unit

Value

OBD Requirements

-

OBD2

OBD Requirements

-

OBD

OBD Requirements

-

OBD and OBD2

OBD Requirements

-

OBD1

OBD Requirements

-

No OBD

OBD Requirements

-

EOBD

OBD Requirements

-

EOBD and OBD2

OBD Requirements

-

EOBD and OBD

OBD Requirements

-

EOBD, OBD and OBD2

OBD Requirements

-

JOBD

OBD Requirements

-

JOBD and OBD2

OBD Requirements

-

JOBD and EOBD

OBD Requirements

-

JOBD, EOBD and OBD2


PID 1E 每 Power Take Off (PTO) Status

Provides an indication of the current operating status of the power take off.

Possible values for PID 1E are:

PID Description

Unit

Value

Power Take Off (PTO) Status

-

OFF

Power Take Off (PTO) Status

-

ON


PID 1F 每 Time Since Engine Start

Provides an indication of elapsed time since the engine was started.

Possible values for PID 1F are:

PID Description

Unit

Value

Time Since Engine Start

minutes

XXXXX


PID 21 每 Distance Traveled While MIL is Activated

Provides an indication of the total distance the vehicle traveled while the MIL was illuminated.

Possible values for PID 21 are:

PID Description

Unit

Value

Distance Traveled While MIL Activated

km / miles

XXXXX / XXXXX


PID 22 每 Fuel Rail Pressure Relative to Vacuum

Provides a calculated value indicating current fuel rail pressure at the engine, referenced to manifold vacuum (relative pressure)

Possible values for PID 22 are:

PID Description

Unit

Value

Fuel Rail Pressure

kPa / PSI

XXXX.XXX / XXX.X


PID 23 每 Fuel Rail Pressure

Provides a calculated value indicating current fuel rail pressure at the engine, referenced to the atmosphere (gauge pressure).

Possible values for PID 23 are:

PID Description

Unit

Value

Fuel Rail Pressure

kPa / PSI

XXX / XX.X


PID 24 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 24 are:

PID Description

Unit

Value

Bank 1 - Sensor 1

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 25 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 25 are:

PID Description

Unit

Value

Bank 1 - Sensor 2

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 26 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 26 are:

PID Description

Unit

Value

Bank 1 - Sensor 3

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 27 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 27 are:

PID Description

Unit

Value

Bank 1 - Sensor 4

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 28 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 28 are:

PID Description

Unit

Value

Bank 2 - Sensor 1

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 29 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 29 are:

PID Description

Unit

Value

Bank 2 - Sensor 2

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 2A 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 2A are:

PID Description

Unit

Value

Bank 2 - Sensor 3

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 2B 每 Oxygen Snesor Equivalence Ratio / Voltage

Provides an indication of the equivalence ratio and voltage for linear or wide-ratio oxygen sensors.

Possible values for PID 2B are:

PID Description

Unit

Value

Bank 2 - Sensor 4

(wide range O2S)

Equiv Ratio

X.XXX

VDC

XXX.X


PID 2C 每 Commanded EGR

Provides an indication of the commanded EGR flow rate.

Possible values for PID 2C are:

PID Description

Unit

Value

Commanded EGR

%

XXX.X


PID 2D 每 EGR Error

Provides a calculated value indicating the amount of EGR error as a percentage of commanded EGR. Positive numbers represent that actual EGR is greater than commanded EGR, negative numbers represent that actual EGR is less than commanded EGR.

Possible values for PID 2D are:

PID Description

Unit

Value

EGR Error

%

XXX.X


PID 2E 每 Commanded Evaporative Purge

Provides an indication of the commanded evaporatifve purge flow rate.

Possible values for PID 2E are:

PID Description

Unit

Value

Commanded Evaporative Purge

%

XXX.X


PID 2F 每 Fuel Level Input

Provides an indication of the amount of fuel currently available, as a percentage of nominal fuel tank capacity.

Possible values for PID 2F are:

PID Description

Unit

Value

Fuel Level Input

%

XXX.X


PID 30 每 Number of Warm-ups Since DTCs Cleared

Provides an indication of the number of OBD warm-up cycles completed since DTCs were last cleared from the vehicle's computer (by external test equipment through MODE $04, or in some cases, through battery disconnection).

Possible values for PID 30 are:

PID Description

Unit

Value

Number of Warm-ups Since DTC Cleared

warm-up cycles

XXX


PID 31 每 Distance Since DTCs Cleared

Provides an indication of the distance traveled since DTCs were last cleared from the vehicle's computer (by external test equipment through MODE $04, or in some cases, through battery disconnection).

Possible values for PID 31 are:

PID Description

Unit

Value

Distance Since DTCs Cleared

km / miles

XXXX / XXXX


PID 32 每 EVAP System Vapor Pressure

Provides an indication of the current EVAP system vapor pressure.

Possible values for PID 32 are:

PID Description

Unit

Value

EVAP System Vapor Pressure

kPa / in. H2O

XXXX.XX / XX.XXXX


PID 33 每 Barometric Pressure

Provides an indication of the barometric pressure used by the vehicle's computer.

Possible values for PID 33 are:

PID Description

Unit

Value

Barometric Pressure

kPa / in. Hg

XXX / XX.X


PID 3C~3F 每 Catalyst Temperature

Provides an indication of current catalytic converter temperature.

Possible values for PID 3C through 3F are:

PID Description

Unit

Value

Catalyst Temperature Bank 1 Sensor 1 (PID 3C)

C / F

XXXX.X / XXXX.X

Catalyst Temperature Bank 2 Sensor 1 (PID 3D)

C / F

XXXX.X / XXXX.X

Catalyst Temperature Bank 1 Sensor 2 (PID 3E)

C / F

XXXX.X / XXXX.X

Catalyst Temperature Bank 2 Sensor 2 (PID 3F)

C / F

XXXX.X / XXXX.X


PID 41 每 Monitor Status this Driving Cycle

Provides an indication of the enable / completion status for the current monitoring cycles for all monitors supported by the vehicle.

Possible values for PID 41 are:

PID Description

Unit

Value

OBD Requirements

-

OBD2

OBD Requirements

-

OBD

OBD Requirements

-

OBD and OBD2

OBD Requirements

-

OBD1

OBD Requirements

-

No OBD

OBD Requirements

-

EOBD

OBD Requirements

-

EOBD and OBD2

OBD Requirements

-

EOBD and OBD

OBD Requirements

-

EOBD, OBD and OBD2

OBD Requirements

-

JOBD

OBD Requirements

-

JOBD and OBD2

OBD Requirements

-

JOBD and EOBD

OBD Requirements

-

JOBD, EOBD and OBD2


PID 42 每 Control Module Voltage

Provides an indication of the voltage supplied to the control module.

Possible values for PID 42 are:

PID Description

Unit

Value

Control Module Voltage

VDC

XX.XXX


PID 43 每 Absolute Load Value

Provides an absolute value indicating the percent of engine capacity that is currently being used.

Possible values for PID 43 are:

PID Description

Unit

Value

Absolute LOAD Value

%

XXX.X


PID 44 每 Commanded Equivalence Ratio

Provides an indication of the current commanded air / fuel ratio.

Possible values for PID 44 are:

PID Description

Unit

Value

Commanded Equivalence Ratio

-

X.XXX


PID 45 每 Relative Throttle Position

Provides an indication of the relative ("learned") throttle position. The value may be displayed as either a "low-to-high" percentage (0% at closed throttle, 95% at wide open throttle) or as a "high-to-low" percentage (high at idle, low at wide open throttle).

Possible values for PID 45 are:

PID Description

Unit

Value

Relative Throttle Position

%

XXX.X


PID 46 每 Ambient Air Temperature

Provides an indication of the current ambient air temperature.

Possible values for PID 46 are:

PID Description

Unit

Value

Ambient Air Temperature

C / F

XXX / XXX


PID 49-4B 每 Accelerator Pedal Position

Provides an indication of absolute accelerator pedal position as a percentage. The value may be displayed as either a "low-to-high" percentage (1% at closed pedal, 95% at wide open pedal) or as a "higth-to-low" percentage (high at closed pedal, low at wide open pedal).

Possible values for PID 49 through 4B are:

PID Description

Unit

Value

Accelerator Pedal Position D

%

XXX.X

Accelerator Pedal Position E

%

XXX.X

Accelerator Pedal Position F

%

XXX.X


PID 4C 每 Commanded Throttle Actuator Control

Provides an indication of the currently commanded throttle actuator control position, as a percentage of full range.

Possible values for PID 4C are:

PID Description

Unit

Value

Commanded Throttle Actuator Control

%

XXX.X


PID 4D 每 Minutes Run by the Engine While MIL Activated

Provides an indication of the total time during which the vehicle was operated while the MIL was illuminated.

Possible values for PID 4D are:

PID Description

Unit

Value

Minutes Run by the Engine While MIL Activated

minutes

XXXXX


PID 4E 每 Time Since DTCs Cleared

Provides an indication of elapsed time since DTCs were last cleared from the vehicle's computer (by external test equipment through MODE $04, or in some cases, through battery disconnection).

Possible values for PID 4E are:

PID Description

Unit

Value

Time Since DTCs Cleared

minutes

XXXXX





MODE 2 每 Powertrain Freeze Frame Data

In OBD2 systems, when an emissions-related engine malfunction occurs that causes a DTC to set, a record or snapshot of actual engine conditions (not default or substituted values used by the vehicle*s on-board computer) at the time that the malfunction occurred is also saved in the vehicle*s computer memory. The record saved is called ※Freeze Frame data.§ Saved engine conditions include, but are not limited to: engine speed, open or closed loop operation, fuel system commands, coolant temperature, calculated load value, fuel pressure, vehicle speed, air flow rate, and intake manifold pressure.

MODE 2, Powertrain Freeze Frame Data, retrieves Freeze Frame Data from the vehicle*s on-board computer.

(NOTE) If more than one malfunction is present that causes more than one DTC to be set, only the code with the highest priority will contain Freeze Frame data. The priority code is the one that has commanded the MIL on.

(NOTE) A Misfire or Fuel System Fault will overwrite all other Freeze Frame Data.


MODE 3 每 Emission-related Diagnostic Trouble Codes (DTCs)

Diagnostic Trouble Codes (DTCs) are alpha-numeric codes that are used to identify a problem that is present in any of the systems that are monitored by the vehicle*s on-board computer. When the vehicle's on-board computer detects a failure in an emissions-related component or system, the computer's internal diagnostic program assigns a Diagnostic Trouble Code (DTC) that points to the system (and subsystem) where the fault was found and saves the code in the computer's memory (see DIAGNOSTIC TROUBLE CODES for more information).

There are two types of DTCs used for emissions-related faults in OBD2 systems: Type ※A§ (※hard§ codes) and Type ※B§ (※pending§ codes). Type ※A§ codes are ※One Trip§ codes. Type ※B§ codes are usually ※Two Trip§ codes. MODE 3, Emission-related Diagnostic Trouble Codes (DTCs), retrieves ※hard§ codes from the vehicle*s on-board computer (※pending§ codes are retrieved by MODE 7).


MODE 4 每 Clear / Reset Emissions-related Diagnostic Information

MODE 4, Clear / Reset Emissions-related Diagnostic Information, clears (erases) all diagnostic information (DTCs, Freeze Frame Data, O2 sensor test results, Monitor status, etc.) from the computer*s memory.

(NOTE) This function is generally performed only after codes have been retrieved, and necessary corrective actions have been performed. DO NOT erase diagnostic information from the vehicle's computer until repairs have been accomplished. If the data is erased, valuable information that might help troubleshoot the problem will be lost.


MODE 5 每 Oxygen Sensor Test Results

OBD2 regulations require that applicable vehicles monitor and test operation of the oxygen (O2) sensors to identify problems that can affect fuel efficiency and vehicle emissions. These tests are performed automatically when engine operating conditions are within predefined limits. Results of these tests are stored in the on-board computer's memory. Once stored, test results are retained in the computer*s memory until they are overwritten by more current test results.

MODE 5, Oxygen Sensor Test Results, retrieves test results for the most recently completed tests of the vehicle*s oxygen sensor(s).


Oxygen Sensor Designations

Vehicles are equipped with multiple O2 sensors. O2 sensors are installed both upstream of (before) and downstream of (after) the exhaust system Catalytic Converters. The name of an O2 sensor identifies its location in the exhaust system. The name of each O2 sensor is made up of three parts:

O2S XX YY -or- O2S X Y

O2S -this is the basic designation for all O2 sensors.

X or XX - These characters identify the location of the O2 sensor in relation to a cylinder bank. An O2 sensor for cylinder bank 1 is identified by the designation ※1§ or "B1"; a sensor for cylinder bank 2 is identified as ※2§ or "B2."

(NOTE) ※Bank One§ indicates the side of the engine where cylinder number one is located (V-type engines). Bank Two is opposite of Bank One.

Y or YY - These characters identity the location of the O2 sensor in relation to the exhaust system catalyst. An O2 sensor located upstream of the catalyst is identified by the designation§1§ or "S1", a sensor located downstream of the Catalytic Converter is identified as ※2§ or "S2."

For example, O2S12 or O2SB1S2 is the designation for the downstream O2 sensor for cylinder bank 1.


Oxygen Sensor Test Results

Oxygen sensor test results include the following information:

$01 每 Rich-to-lean threshold voltage

$02 每 Lean-to-rich threshold voltage

$03 每 Low sensor voltage switch time

$04 每 High sensor voltage switch time

$05 每 Rich-to-lean sensor switch time

$06 每 Lean-to-rich sensor switch time

$07 每 Minimum voltage for test cycle

$08 每 Maximum voltage for test cycle

$09 每 Time between sensor transitions


MODE 6 每 Non-continuous Test Results

MODE 6, Non-continuous Test Results, retrieves test results for emission-related powertrain components and systems that are not continuously monitored. The tests available are determined by the vehicle manufacturer.

This diagnostic mode does not command the vehicle*s computer to perform the tests, but retrieves results from the most recently performed tests from the computer*s memory.


MODE 7 每 Continuous Monitors Test Results

Diagnostic Trouble Codes (DTCs) are alpha-numeric codes that are used to identify a problem that is present in any of the systems that are monitored by the vehicle*s on-board computer. When the vehicle's on-board computer detects a failure in an emissions-related component or system, the computer's internal diagnostic program assigns a Diagnostic Trouble Code (DTC) that points to the system (and subsystem) where the fault was found and saves the code in the computer's memory (see DIAGNOSTIC TROUBLE CODES for more information).

There are two types of DTCs used for emissions-related faults in OBD2 systems: Type ※A§ (※hard§ codes) and Type ※B§ (※pending§ codes). Type ※A§ codes are ※One Trip§ codes. Type ※B§ codes are usually ※Two Trip§ codes. MODE 7, Emission-related Diagnostic Trouble Codes (DTCs), retrieves ※pending§ codes from the vehicle*s on-board computer (※hard§ codes are retrieved by MODE 3).


MODE 8 每 Control of On-board Tests and Devices

MODE 8 , Control of On-board Tests and Devices, is a bidirectional test mode that allows external test equipment (such as a Code Reader or Scan Tool) of an on-board system, test, or component. This diagnostic mode lets the external device command the vehicle*s on-board computer to initiate or perform one or more specific tests, and retrieve test results.

The specific components/systems for which test results are available vary between vehicle manufacturers, makes and models. Currently, implementation of MODE 8 is limited. However, CARB is reviewing this functionality for possible future expansion.


MODE 9 每 Vehicle Information

MODE 9, Vehicle Information, retrieves vehicle-specific reference information including the Vehicle Identification Number (VIN), Calibration IDs, Calibration Verification Number and In每use performance tracking counts.