P0137
DTC P0137: Heated Oxygen Sensor Circuit Low Voltage (sensor 2)Heated 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. 2 of the heated oxygen sensor (rear) is grounded with ECM (terminal No. 75)
- The ECM
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
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 heater (front) monitor
- Heated oxygen sensor heater (rear) monitor
- Air/fuel ratio feedback monitor
Sensor (The sensor below is determined to be normal)
- Volume air flow 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.
- 3 minutes or more have passed since the engine starting sequence was completed.
Judgement Criterion
- Heated oxygen sensor output voltage is lower than 0.2 volt for 2 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 20 OBD-II Drive Cycle Pattern Lists.
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.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
- MB991658: Test Harness Set
STEP 1. Measure the sensor output voltage at heated oxygen sensor (rear) connector C-11 by backprobing
1. Do not disconnect the connector C-11.
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 1 and ground by backprobing under the following driving.
a. Transaxle: 2nd speed (A/T: *L* range)
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.
Q: Is the measured voltage within the specified range?
YES: Go to Step 2.
NO: Go to Step 6.
STEP 2. Measure the sensor output voltage at ECM connector C-115
1. Do not disconnect connector C-115
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 73 and ground by backprobing under the following driving.
a. Transaxle: 2nd speed (A/T: *L* range)
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 3.
NO: Go to Step 5.
STEP 3. Check harness connector C-11 at heated oxygen sensor (rear) and harness connector C-115 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 4.
NO: Repair or replace it. Then go to Step 13.
STEP 4. Check the trouble symptoms.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 20 OBD-II Drive Cycle Pattern Lists.
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0137 set?
YES: Replace the ECM or the PCM. Then go to Step 13.
NO: It can be assumed that this malfunction is intermittent.
STEP 5. Check harness connector C-11 at heated oxygen sensor (rear) and harness connector C-115 at ECM
Q: Is the harness connector in good condition?
YES: Repair harness wire between heated oxygen sensor (rear) connector C-11 (terminal No. 1) and ECM connector C-115
NO: Repair or replace it. Then go to Step 13.
STEP 6. Check harness connector C-11 at heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 8.
NO: Repair or replace it. Then go to Step 13.
STEP 7. Measure the sensor offset voltage at ECM connector C-115
1. Do not disconnect connector C-115
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 75
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 9.
NO: Go to Step 8.
STEP 8. Check harness connector C-115 at ECM
Q: Is the harness connector in good condition?
YES: Repair harness wire between heated oxygen sensor (rear) connector C-11 (terminal No. 2) and ECM connector C-115 (terminal No. 75)
NO: Repair or replace it. Then go to Step 13.
STEP 9. Check harness connector C-115 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 10.
NO: Repair or replace it. Then go to Step 13.
STEP 10. Check for harness damage between heated oxygen sensor (rear) connector C-11 (terminal No. 2) and ECM connector C-115 (terminal No. 75)
Q: Is the harness wire in good condition?
YES: Go to Step 11.
NO: Repair it. Then go to Step 13.
STEP 11. Check for short circuit to ground and harness damage between heated oxygen sensor (rear) connector C-11 (terminal No. 1) and ECM connector C-115
Q: Is the harness wire in good condition?
YES: Go to Step 12.
NO: Repair it. Then go to Step 13.
STEP 12. Check the heated oxygen sensor (rear).
1. Disconnect the heated oxygen sensor (rear) connector C-11 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 degrees C (176 degrees F) or higher.
3. Drive at 50 km/h (31mph) or more for 10 minutes.
4. Connect a digital voltage meter between terminal No. 1 and terminal No. 2.
5. Measure the output voltage of heated oxygen sensor under the following driving.
- Transaxle: 2nd speed (A/T: *L* range)
- Drive with wide open throttle
- Engine: 3,500 r/min or more
Standard value: 0.6 - 1.0 volt.
NOTE: If the sufficiently high temperature [of approximate 400 degrees C (752 degrees F) or more] is not reached although the heated oxygen sensor is normal, the output voltage would be possibly low although the rich air/fuel ratio.
Q: Is the measured voltage between 0.6 and 1.0 volt?
YES: Replace the ECM or the PCM. Then go to Step 13.
NO: Replace the heated oxygen sensor (rear). Then go to Step 13.
STEP 13. 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 20 OBD-II Drive Cycle Pattern Lists.
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0137 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.