P0431
TECHNICAL DESCRIPTION- The signal from the rear heated oxygen sensor differs from the front heated oxygen sensor. That is because the catalytic converter purifies exhaust gas. When the catalytic converter has deteriorated, the signal from the front heated oxygen sensor becomes similar to the rear heated oxygen sensor.
- The ECM
DTC SET CONDITIONS
Check Conditions
- Engine speed is lower than 3,000 r/min.
- Volume air flow sensor output frequency is between 69 and 169 Hz.
- Intake air temperature is higher than -10 °C (14 ° F).
- Barometric pressure is higher than 76 kPa (11 psi).
- The throttle valve is open.
- Under the closed loop air/fuel ratio control.
- Vehicle speed is 1.5 km/h (0.93 mph) or more.
- Monitoring time: 84 seconds.
Judgment Criteria
- The left bank heated oxygen sensor (rear) signal and left bank heated oxygen sensor (front) signal are similar.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Left bank side catalytic converter deteriorated.
- Left bank heated oxygen sensor failed.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools
MB991502: Scan Tool(MUT-II)
STEP 1. Check the exhaust leaks.
Q: Are there any abnormalities?
YES: Go to Step 2.
NO: Repair it. Then go to Step 7.
STEP 2. Using scan tool MB991502, check data list item 59: Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK"(OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to the data reading mode for item 59, Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).
- Warming up the engine. When the engine is revved, the output voltage should repeat 0 volt and 0.6 to 1.0 volt alternately.
4. Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the sensor operating properly?
YES: Go to Step 3.
NO: Refer to DTC P0156 - O(2) Sensor Circuit Malfunction (bank 2 sensor 2), DTC P0159 - O(2) Sensor Circuit Slow Response (bank 2 sensor 2).
STEP 3. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor Bank 2, Sensor 1 (left front).
1. Start the engine and run at idle.
2. Set scan tool MB991502 to the data reading mode for item 11, Heated Oxygen Sensor Bank 2, Sensor 1 (left front).
- Warming up the engine. When the engine is revved, the output voltage should be 0.6 to 1.0 volt.
3. Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the sensor operating properly?
YES: Go to Step 4.
NO: Refer to DTC P0150 - O(2) Sensor Circuit Malfunction (bank 2 sensor 1), DTC P0153 - O(2) Sensor Circuit Slow Response (bank 2 sensor 1 ).
STEP 4. Using scan tool MB991502, check data list item 11: Heated Oxygen Sensor Bank 2, Sensor 1 (left front).
1. Start the engine and run at idle.
2. Set scan tool MB991502 to the data reading mode for item 11, Heated Oxygen Sensor Bank 2, Sensor 1 (left front).
3. Keep the engine speed at 2,000 r/min.
- 0 - 0.4 and 0.6 - 1.0 volt should alternate 15 times or more within 10 seconds.
4. Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the sensor operating properly?
YES: Go to Step 5.
NO: Replace the left bank heated oxygen sensor (front). Then go to Step 7.
STEP 5. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 3 - Catalytic Converter Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0431 is output?
YES: Replace the left bank side catalytic converter. Then go to Step 6.
NO: The inspection is complete.
STEP 6. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 3 - Catalytic Converter Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0431 is output?
YES: Replace the ECM or PCM. Then go to Step 7.
NO: The inspection is complete.
STEP 7. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 3 - Catalytic Converter Monitor.
2. Check the diagnostic trouble code(DTC).
Q: Is the DTC P0431 is output?
YES: Retry the troubleshooting.
NO: The inspection is complete.