P0137

DTC P0137: Heated Oxygen Sensor Circuit Low Voltage (bank 1, sensor 2)














CIRCUIT OPERATION

- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 56) from the output terminal (terminal No. 4) of the right bank heated oxygen sensor (rear).

- Terminal No. 2 of the right bank heated oxygen sensor (rear) is grounded with ECM
(terminal No. 57).

- The ECM applies an off set voltage of 0.5 volt to terminal No. 2 of the right bank heated oxygen sensor (rear).

TECHNICAL DESCRIPTION

- The output signal of the right bank heated oxygen sensor (front) is compensated by the output signal of the right bank heated oxygen sensor (rear).

- The ECM checks for the right bank heated oxygen sensor (rear) output voltage.

DESCRIPTIONS OF MONITOR METHODS

Right bank 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) heater monitor

- Heated oxygen sensor (rear) heater monitor

- Heated oxygen sensor (front) 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






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

- Right bank heated oxygen sensor (rear) 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 21 Monitors, Trips, Drive Cycles and Readiness Codes.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

- Right bank heated oxygen sensor (rear) failed.

- Connector damage.

- Harness 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

- MB998464: Test Harness

STEP 1. Check harness connector B-02 at the right bank heated oxygen sensor (rear) and harness connector B-10 at the ECM for damage.

Q. Is the harness connector in good condition?

YES Go to Step 2.
NO Repair it. Harness Connector Inspection.
Then go to Step 5.
STEP 2. Check the right bank heated oxygen sensor (rear).

(1)Disconnect the right bank heated oxygen sensor (rear) connector B-02 and connect test harness special tool, MB998464, to the connector on the right bank 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 (31 mph) or more for 10 minutes.





(4)Connect a digital voltage meter between terminal No. 2 (black clip) and terminal No. 4
(white clip).
(5)Measure the output voltage of heated oxygen sensor under the following driving.
1. Transaxle: 2nd speed

2. Drive with wide open throttle

3. Engine: 3,500 r/min or more
Standard value: 0.6 - 1.0 volts
NOTE:
If the temperature of sensing area does not reach the high temperature [of approximately 400°C (752°F) or more] even though the oxygen sensor is normal, the output voltage would be possibly low in spite of the rich air-fuel ratio.

NOTE:
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 voltage between 0.6 and 1.0 volts?

YES Go to Step 3.

NO Replace the right bank heated oxygen sensor (rear). Then go to Step 5.

STEP 3. Check for harness between the right bank heated oxygen sensor
(rear) connector B-02 and the ECM connector B-10.

(1)Disconnect the right bank heated oxygen sensor (rear) connector B-02 and the ECM connector B-10.





(2)Measure the resistance between the heated oxygen sensor connector B-02 and the ECM connector B-10.
4. Connector B-02 (terminal No. 2) and connector B-10 (terminal No. 57).

5. Connector B-02 (terminal No. 4) and connector B-10 (terminal No. 56).

- Should be less than 2 ohms.





(3)Check for the continuity oxygen sensor connector B-02 and ground.
6. Connector B-02 (terminal No. 2) and ground.

7. Connector B-02 (terminal No. 4) and ground.

- Not continuity.

Q. Is the harness wire in good condition?

YES Go to Step 4.

NO Repair it. Harness Connector Inspection.
Then go to Step 5.

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 21 Monitors, Trips, Drive Cycles and Readiness Codes

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P0137 set?

YES Replace the ECM. When the ECM is replaced, register the ID code. Refer to ID registration procedure manual - ID codes registration judgement table [Vehicles with KOS] or ID registration procedure manual - ID codes registration judgement table [Vehicles with WCM]. Then go to Step 5.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 5. 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 21 Monitors, Trips, Drive Cycles and Readiness Codes.

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P0137 set?

YES Retry the troubleshooting.
NO The inspection is complete.