P0137
DTC P0137: Heated Oxygen Sensor (rear) Circuit Low VoltageHeated Oxygen Sensor (Rear) Circuit (Part 1):
Heated Oxygen Sensor (Rear) Circuit (Part 2):
CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 40) from the output terminal (terminal No. 3) of the heated oxygen sensor (rear).
- Terminal No. 4 of the heated oxygen sensor (rear) is grounded with ECM (terminal No. 41).
- The ECM applies an offset voltage of 0.5 volt to terminal No. 4 of the heated oxygen sensor (rear).
TECHNICAL DESCRIPTION
- The output signal of the heated oxygen sensor (front) is compensated by the output signal of the heated oxygen sensor (rear).
- The ECM checks for the heated oxygen sensor (rear) output voltage.
DESCRIPTIONS OF MONITOR METHODS
Heated oxygen sensor (rear) output voltage is under the specified range.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Heated oxygen sensor (front) monitor
- Heated oxygen sensor (front) heater monitor
- Heated oxygen sensor (rear) heater monitor
- Heated oxygen sensor (front) inactive monitor
- Heated oxygen sensor offset voltage monitor
- Air/fuel ratio feedback monitor
Sensor (The sensor below is determined to be normal)
- Mass airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor
DTC SET CONDITIONS
Logic Flow Chart
Logic Flow Chart:
Check Conditions
- Heated oxygen sensor offset voltage is between 0.4 and 0.6 volt.
- Battery positive voltage is between 11 and 16.5 volts.
- More than 330 seconds have passed since the engine starting sequence was completed.
Judgement Criterion
- Heated oxygen sensor (rear) output voltage is lower than 0.2 volt for 2 seconds.
FAIL-SAFE AND BACKUP FUNCTION
- None
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22. OBD- II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Heated oxygen sensor (rear) failed.
- Open or shorted circuit in heated oxygen sensor (rear) output line or harness damage.
- Open circuit in heated oxygen sensor (rear) ground line or harness damage.
- Connector damage.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991658: Test Harness
- MB992110: Power Plant ECU Check Harness
STEP 1. Using scan tool MB991958, check data list item AD: Heated Oxygen Sensor (rear).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991958 to the data reading mode for item AD, Heated Oxygen Sensor (rear).
a. Transaxle: 2nd speed
b. Drive with wide open throttle
c. Engine: 3,500 r/min
- The output voltages should be between 0.6 and 1.0 volt.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : It can be assumed that this malfunction is intermittent.
NO : Go to Step 2.
STEP 2. Measure the sensor output voltage at heated oxygen sensor (rear) connector D-35 by backprobing
1. Do not disconnect the connector D-35.
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 3 and ground by backprobing under the following driving.
a. Transaxle: 2nd speed
b. Drive with wide open throttle
c. Engine: 3,500 r/min or more
- The output voltage should be between 1.0 and 1.5 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage within the specified range?
YES : Go to Step 3.
NO : Go to Step 8.
STEP 3. Check harness connector B-09 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 4.
NO : Repair or replace it. Then go to Step 14.
STEP 4. Measure the sensor output voltage at ECM connector B-09 by using power plant ECU check harness special tool MB992110.
1. Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 40 and ground by backprobing under the following driving.
a. Transaxle: 2nd speed
b. Drive with wide open throttle
c. Engine: 3,500 r/min or more
- The output voltage should be between 1.0 and 1.5 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 1.0 and 1.5 volts?
YES : Go to Step 5.
NO : Go to Step 7.
STEP 5. Check harness connector D-35 at heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 6.
NO : Repair or replace it. Then go to Step 14.
STEP 6. Using scan tool MB991958, check data list item AD: Heated Oxygen Sensor (rear).
1. Start the engine and run at idle.
2. Set scan tool MB991958 to the data reading mode for item AD, Heated Oxygen Sensor (rear).
a. Transaxle: 2nd speed
b. Drive with wide open throttle
c. Engine: 3,500 r/min or more
- The output voltage should be between 0.6 and 1.0 volt.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES : It can be assumed that this malfunction is intermittent.
NO : Replace the ECM. When the ECM is replaced, register the ID code. Then go to Step 14.
STEP 7. Check harness connector D-35 at heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?
YES : Check harness connectors A-13 and C-45 at intermediate connectors for damage, and repair or replace as required. Then go to Step 14.
NO : Repair or replace it. Then go to Step 14.
STEP 8. Check harness connector D-35 at heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 9.
NO : Repair or replace it. Then go to Step 14.
STEP 9. Check harness connector B-09 at ECM for damage.
Q: Is the harness connector in good condition?
YES : Go to Step 10.
NO : Repair or replace it. Then go to Step 14.
STEP 10. Measure the sensor offset voltage at ECM connector B-09 by using power plant ECU check harness special tool MB992110.
1. Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 41 and ground.
- Voltage should be between 0.4 and 0.6 volt.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 0.4 and 0.6 volt?
YES : Go to Step 11.
NO : Check harness connectors A-13 and C-45 at intermediate connectors for damage, and repair or replace as required. Then go to Step 14.
STEP 11. Check for harness damage between heated oxygen sensor (rear) connector D-35 (terminal No. 4) and ECM connector B-09 (terminal No. 41).
NOTE: Check harness after checking intermediate connectors A-13 and C-45. If intermediate connectors are damaged, repair or replace them. Then go to Step 14.
Q: Is the harness wire in good condition?
YES : Go to Step 12.
NO : Repair it. Then go to Step 14.
STEP 12. Check for short circuit to ground and harness damage between heated oxygen sensor (rear) connector D-35 (terminal No. 3) and ECM connector B-09 (terminal No. 40).
NOTE: Check harness after checking intermediate connectors A-13 and C-45. If intermediate connectors are damaged, repair or replace them. Then go to Step 14.
Q: Is the harness wire in good condition?
YES : Go to Step 13.
NO : Repair it. Then go to Step 14.
STEP 13. Check the heated oxygen sensor (rear).
1. Disconnect the heated oxygen sensor (rear) connector D-35 and connect test harness special tool MB991658 to the connector on the heated oxygen sensor (rear) side.
2. Warm up the engine until engine coolant temperature reaches 80°C (176°F) or higher.
3. Drive at 50 km/h (31mph) or more for 10 minutes.
4. Connect a digital voltage meter between terminal No. 3 and terminal No. 4.
5. Measure the output voltage of heated oxygen sensor under the following driving.
- Transaxle: 2nd speed
- Drive with wide open throttle
- Engine: 3,500 r/min or more
Standard value: 0.6 - 1.0 V
NOTE:
- If the temperature of sensing area does not reach the high temperature [of approximately 400°C (752°F) or more] even though the heated oxygen sensor is normal, the output voltage would be possibly low in spite of the rich air/fuel ratio.
- When the vehicle is driven with high loads, the temperature of the sensing area of the heated oxygen sensor is sufficiently high. Thus, it is not necessary to apply the voltage to the heater.
Q: Is the measured voltage between 0.6 and 1.0 volt?
YES : Replace the ECM. When the ECM is replaced, register the ID code. Then go to Step 14.
NO : Replace the heated oxygen sensor (rear). Then go to Step 14.
STEP 14. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22. OBD- II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0137 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.