DTC P2A00 A/F Sensor Circuit Slow Response (Bank 1 Sensor 1); DTC P2A03 A/F Sensor Circuit Slow Response (Bank 2 Sensor 1): Wiring Diagram
WARNING: This page is about a different car, the 2006 Lexus RX 400h. However, it is still accessible from the selected car via links, so may be relevant.
Refer to DTC P2195 .
HINT:
Intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using the intelligent tester.
- Connect the intelligent tester to the DLC3.
- Put the engine in inspection mode (See INSPECTION MODE PROCEDURE ).
- Start the engine and turn the tester ON.
- Warm up the engine at an engine speed of 2,500 RPM for approximately 90 seconds.
- On the intelligent tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
- Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
- Monitor the output voltages of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
- Each sensor reacts in accordance with increases in the fuel injection volume.
Standard
TESTER DISPLAY DIAGNOSIS PROCEDURE
| Tester Display (Sensor) | Injection Volume | Status | Voltage |
|---|---|---|---|
| AFS B1S1 or AFS B2S1 (A/F) | +25 % | Rich | Less than 3.0 |
| AFS B1S1 or AFS B2S1 (A/F) | -12.5 % | Lean | More than 3.35 |
| O2S B1S2 or O2S B2S2 (HO2) | +25 % | Rich | More than 0.55 |
| O2S B1S2 or O2S B2S2 (HO2) | -12.5 % | Lean | Less than 0.4 |
NOTE:
The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.
AIR-FUEL RATIO CHART
| Case | A/F Sensor (Sensor 1) Output Voltage | HO2 Sensor (Sensor 2) Output Voltage | Main Suspected Trouble Area | ||
|---|---|---|---|---|---|
| 1 | Injection Volume +25% -12.5% |
Injection Volume +25% -12.5% |
- | ||
| Output Voltage More than 3.35 V Less than 3.0 V |
Output Voltage More than 0.55 V Less than 0.4 V |
||||
| 2 | Injection Volume +25% -12.5% |
Injection Volume +25% -12.5% |
|
||
| Output Voltage Almost no reaction |
Output Voltage More than 0.55 V Less than 0.4 V |
||||
| 3 | Injection Volume +25% -12.5% |
Injection Volume +25% -12.5% |
|
||
| Output Voltage More than 3.35 V Less than 3.0 V |
Output Voltage Almost no reaction |
||||
| 4 | Injection volume +25% -12.5% |
Injection Volume +25% -12.5% |
|
||
| Output Voltage Almost no reaction |
Output Voltage Almost no reaction |
||||
- Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
- To display the graph, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, and press the YES button and then the ENTER button followed by the F4 button.
HINT:
- DTC P2A00 or P2A03 may be also set, when the air-fuel ratio is stuck rich or lean.
- A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
- A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run lean.
- Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was LEAN or RICH, and other data from the time the malfunction occurred.
- CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)
- Connect the intelligent tester to the DLC3.
- Turn the ignition switch ON.
- Turn the tester ON.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
- Read DTCs.
Result
RESULT CHARTDisplay (DTC Output) Proceed to P2A00 and/or P2A03 A P2A00 and/or P2A03 and other DTCs B HINT:
If any DTCs other than P2A00 or P2A03 are output, troubleshoot those DTCs first.
B: GO TO DIAGNOSTIC TROUBLE CODE CHART
A: Go to next step
- READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF A/F SENSOR)
- Connect the intelligent tester to the DLC3.
- Put the engine in inspection mode (See INSPECTION MODE PROCEDURE ).
- Start the engine.
- Turn the tester ON.
- Warm up the Air-Fuel Ratio (A/F) sensor at an engine speed of 2,500 RPM for 90 seconds.
- On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / SNAPSHOT / MANUAL SNAPSHOT / USER DATA / AFS B1S1 or AFS B2S1 and ENGINE SPD.
- Check the A/F sensor voltage three times, when the engine is in each of the following conditions:
- While idling (check for at least 30 seconds)
- At an engine speed of approximately 2,500 RPM (without any sudden changes in engine speed)
- Raise the engine speed to 4,000 RPM and then quickly release the accelerator pedal so that the throttle valve is fully closed.
Standard voltage
A/F SENSOR VOLTAGE CHARTCondition A/F Sensor Voltage Variation Reference (1) and (2) Changes at approximately 3.3 V Between 3.1 V and 3.5 V (3) Increases to 3.8 V or more This occurs during engine deceleration when fuel-cut performed HINT:
For more information, see the diagrams below.
HINT:
- If the output voltage of the A/F sensor remains at approximately 3.3 V (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have an open circuit. (this will also happen if the A/F sensor heater has an open circuit.)
- If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have a short circuit.
- The ECM (Included in HV Control ECU) stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and result in a momentary increase in the A/F sensor output voltage.
- The ECM must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM to learn the closed throttle valve position.
- When the vehicle is driven: The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. For the vehicle, this translates to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.
- The A/F sensor is a current output element; therefore, the current is converted into a voltage inside the ECM. Measuring the voltage at the connectors of the A/F sensor or ECM will show a constant voltage result.
NG: Go to step 9
OK: GO TO NEXT STEP
- PERFORM CONFIRMATION DRIVING PATTERN
- CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
- Read DTCs using the intelligent tester.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
Result
RESULT CHARTDisplay (DTC Output) Proceed to P2A00 and/or P2A03 A No output B
B: Go to step 8
A: Go to next step
- REPLACE AIR FUEL RATIO SENSOR
- PERFORM CONFIRMATION DRIVING PATTERN
- CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
- Read DTCs using the intelligent tester.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
Result
RESULT CHARTDisplay (DTC Output) Proceed to No output A P2A00 and/or P2A03 B
B: REPLACE HV CONTROL ECU AND PERFORM CONFIRMATION DRIVING PATTERN
A: Go to next step
- CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO: CHECK FOR INTERMITTENT PROBLEMS
YES: DTC CAUSED BY RUNNING OUT OF FUEL
- INSPECT AIR FUEL RATIO SENSOR
- Disconnect the A3 or A4 A/F sensor connector.
- Measure the resistance between the terminals of the A/F sensor connector.
Standard resistance
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Specified Condition HA1A, HA2A (1) - +B (2) 1.8 Ω to 3.4 Ω at 20°C (68°F) HA1A, HA2A (1) - A1A-, A2A- (4) 10 kΩ or higher - Reconnect the A/F sensor connector.
NG: REPLACE AIR FUEL RATIO SENSOR
OK: GO TO NEXT STEP
- INSPECT A/F RELAY
- Remove the A/F relay from the engine room R/B.
- Measure A/F relay resistance.
Standard resistance
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Specified Condition 3 - 5 10 kΩ or higher 3 - 5 Below 1 Ω (when battery voltage applied to terminals 1 and 2) - Reinstall the A/F relay.
NG: REPLACE A/F RELAY
OK: GO TO NEXT STEP
- CHECK HARNESS AND CONNECTOR (A/F SENSOR -HV CONTROL ECU)
- Disconnect the A3 and A4 A/F sensor connector.
- Turn the ignition switch ON.
- Measure the voltage between the +B terminal of the A/F sensor connector and body ground.
Standard voltage
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Specified Condition +B (2) - Body ground 9 to 14 V - Turn the ignition switch off.
- Disconnect the H33 HV Control ECU connector.
- Measure the resistance between the terminals of the A/F sensor and HV Control ECU.
Standard resistance (Check for open)
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Specified Condition HA1A ( A4-1) - HA1A (H33-4) Below 1 Ω A1A+ (A4-3) - A1A+ (H33-22) Below 1 Ω A1A- (A4-4) - A1A- (H33-30) Below 1 Ω HA2A (A3-1) - HA2A (H33-3) Below 1 Ω A2A+ (A3-3) - A2A+ (H33-23) Below 1 Ω A2A- (A3-4) - A2A- (H33-31) Below 1 Ω Standard resistance (Check for short)
TESTER CONNECTION SPECIFIED CONDITION CHARTTester Connection Specified Condition HA1A( A4-1) or HA1A (H33-4) - Body ground 10 kΩ or higher A1A+ (A4-3) or A1A+ (H33-22) - Body ground 10 kΩ or higher A1A- (A4-4) or A1A- (H33-30) - Body ground 10 kΩ or higher HA2A (A3-1) or HA2A (H33-3) - Body ground 10 kΩ or higher A2A+ (A3-3) or A2A+ (H33-23) - Body ground 10 kΩ or higher A2A- (A3-4) or A2A- (H33-31) - Body ground 10 kΩ or higher - Reconnect the HV Control ECU connector.
- Reconnect the A/F sensor connector.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: GO TO NEXT STEP
- CHECK AIR INDUCTION SYSTEM
- Check the air induction system for vacuum leakage.
OK:
No leakage from air induction system.
NG: REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK: GO TO NEXT STEP
- Check the air induction system for vacuum leakage.
- CHECK PCV HOSE
OK:
PCV hose is connected correctly and is not damaged.
NG: REPAIR OR REPLACE PCV HOSE
OK: GO TO NEXT STEP
- CHECK FUEL PRESSURE
- Check the fuel pressure (See
ON-VEHICLE INSPECTION
).
Standard:
304 to 343 kPa (3.1 to 3.5 kgf/cm 2 , 44.1 to 49.7 psi)
NG: REPAIR OR REPLACE FUEL SYSTEM
OK: GO TO NEXT STEP
- Check the fuel pressure (See
ON-VEHICLE INSPECTION
).
- INSPECT FUEL INJECTOR
- Check the injector injection (See
INSPECTION
).
Standard:
13 cm 3 (0.8 cu in.) or less
NG: REPLACE FUEL INJECTOR ASSEMBLY
OK: GO TO NEXT STEP
- Check the injector injection (See
INSPECTION
).
- REPLACE AIR FUEL RATIO SENSOR
- PERFORM CONFIRMATION DRIVING PATTERN
- CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)
- Read DTCs using the intelligent tester.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
Result
RESULT CHARTDisplay (DTC Output) Proceed to No output A P2A00 and/or P2A03 B
B: REPLACE HV CONTROL ECU
A: GO TO NEXT STEP
- CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO: CHECK FOR INTERMITTENT PROBLEMS
YES: DTC CAUSED BY RUNNING OUT OF FUEL