P0136
DTC P0136: Heated Oxygen Sensor Circuit (sensor 2)Heated Oxygen Sensor (Front) Circuit:
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
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) circuit is switched to 5 volts intentionally when oxygen sensor output is low, and detects the malfunction if the output voltage changes to equal or greater than 4.5 volts. The above procedure is repeated when oxygen sensor is inactive.
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)
- 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
- 3 minutes or more have passed since the engine starting sequence was completed.
- Heated oxygen sensor (rear) signal voltage has continued to be 0.15 volt or lower.
- Engine coolant temperature is higher than 76 degrees C (169 degrees F).
- Engine speed is higher than 1,200 r/min.
- Volumetric efficiency is higher than 25 percent.
- Monitoring time: 7 seconds.
Judgement Criterion
- Input voltage supplied to the ECM
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 11 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 circuit in heated oxygen sensor (rear) output line or connector damage.
- Open circuit in heated oxygen sensor (rear) ground line or 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
STEP 1. Using scan tool MB991958, check data list item 59: 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 59, Heated Oxygen Sensor (rear).
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 0.6 and 1.0 volts.
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-34 by backprobing.
1. Do not disconnect the connector D-34.
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 4 and ground by backprobing.
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 0.6 and 1.0 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 6.
STEP 3. Check harness connector D-34 at heated oxygen sensor (rear) and harness connector C-139 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 4.
NO: Repair or replace it. Then go to Step 11.
STEP 4. Check for open circuit between heated oxygen sensor (rear) connector D-34 (terminal No. 4) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Go to Step 5.
NO: Repair it. Then go to Step 10.
STEP 5. Using scan tool MB991958, check data list item 59: 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 59, Heated Oxygen Sensor (rear).
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 0.6 and 1.0 volts.
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: Replace the ECM or the PCM. Then go to Step 11.
STEP 6. Check harness connector D-34 at heated oxygen sensor (rear) for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 7.
NO: Repair or replace it. Then go to Step 11.
STEP 7. Check the continuity at heated oxygen sensor (rear) harness side connector D-34.
1. Disconnect the connector D-34 and measure at the harness side.
2. Check for the continuity between terminal No. 2 and ground.
- Should be less than 2 Ohms.
Q: Does continuity exist?
YES: Go to Step 10.
NO: Go to Step 8.
STEP 8. Check harness connector C-139 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 9.
NO: Repair or replace it. Then go to Step 11.
STEP 9. Check for open circuit between heated oxygen sensor (rear) connector D-34 (terminal No. 2) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Replace the ECM or the PCM. Then go to Step 11.
NO: Repair it. Then go to Step 11.
STEP 10. Check the heated oxygen sensor (rear).
1. Disconnect the heated oxygen sensor (rear) connector D-34 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 (31 mph) or more for 10 minutes.
4. Connect a digital voltage meter between terminal No. 4 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 (rear) 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 11.
NO: Replace the heated oxygen sensor (rear). Then go to Step 11.
STEP 11. 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 11 OBD-II Drive Cycle Pattern Lists.
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0136 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.