P0136
DTC P0136: Heated Oxygen Sensor Circuit (sensor 2)Heated Oxygen Sensor (rear) 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 °C (168 °F).
- Engine speed is higher than 1,200 r/min.
- Volumetric efficiency is higher than 25 percent.
- Monitoring time: 7 seconds.
Judgment Criteria
- Input voltage supplied to the ECM
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. 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).
- Warm 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: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.
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.
- Warm 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 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. Refer to Harness Connector Inspection. 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).
- Warm 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: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.
NO: Replace the ECM or 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. Refer to Harness Connector Inspection. 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. Refer to Harness Connector Inspection. 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 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 °C (176 °F) or higher.
3. Perform a racing for 5 minutes or more with the engine speed of,500 r/min.
4. Connect a digital voltage meter between terminal No. 4 and terminal No. 2.
5. While repeatedly revving the engine, measure the heated oxygen sensor (front) output voltage.
Standard value: 0.6 - 1.0 volt
CAUTION:
- Be very careful when connecting the jumper wire; incorrect connection can damage the heated oxygen sensor (rear).
- Be careful the heater is broken when voltage of beyond 12 volts is applied to the heated oxygen sensor (rear) heater.
NOTE: If the sufficiently high temperature [of approximate 400 °C (752 °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. Therefore, if the output voltage is low, use a jumper wire to connect the terminal No. 1 and the terminal No. 3 of the heated oxygen sensor (rear) with the positive terminal and the negative terminal of 12 volts power supply respectively, then check again.
Q: Is the measured voltage between 0.6 and 1.0 volt?
YES: Replace the ECM or 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 - Procedure 6 - Other Monitor. 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.