P0037

DTC P0037: Heated Oxygen Sensor Heater Circuit Low (bank 1, sensor 2)






















CIRCUIT OPERATION

- Power is supplied from the MFI relay (terminal No. 2) to the right bank heated oxygen sensor (rear) heater.

- The ECM (terminal No. 49) controls continuity to the right bank heated oxygen sensor
(rear) heater by turning the power transistor in the ECM "ON" and "OFF".

TECHNICAL DESCRIPTION

- The ECM checks whether the heater current is within a specified range when the heater is energized.

- The ECM checks whether the heater voltage is within a specified range when the heater is not energized.

DESCRIPTIONS OF MONITOR METHODS

Right bank heated oxygen sensor heater (rear) current or voltage is out of 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)

- Not applicable
Sensor (The sensor below is determined to be normal)

- Not applicable

DTC SET CONDITION

Logic Flow Chart






Check Conditions

- More than 2 seconds have passed since the engine starting sequence was completed.

- While the right bank heated oxygen sensor (rear) heater is on.

- Battery positive voltage is at between 11 and 16.5 volts.
Judgement Criterion

- The right bank heated oxygen sensor (rear) heater current has continued to be lower than 0.17 ampere for 2 seconds.

Check Conditions

- More than 2 seconds have passed since the engine starting sequence was completed.

- While the right bank heated oxygen sensor (rear) heater is off.

- Battery positive voltage is at between 11 and 16.5 volts.
Judgement Criterion

- The right bank heated oxygen sensor (rear) heater voltage has continued to be lower than 2.0 volts for 2 seconds.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2 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) heater failed.

- Connector damage.

- Harness damage

- ECM failed.

DIAGNOSIS

Required Special Tools:

- 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 or replace it. Harness Connector Inspection.
Then go to Step 6.
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, MD998464, to the connector on the right bank heated oxygen (rear) sensor side.
(2)Measure the resistance between heated oxygen sensor connector terminal No. 1 (red clip) and terminal No. 3 (blue clip).
Standard value: 11 - 18 ohms [at 20°C (68°F)]

Q. Is the measured resistance between 11 and 18 ohms [at 20°C (68°F)]?

YES Go to Step 3.

NO Replace the right bank heated oxygen sensor (rear). Then go to Step 6.

STEP 3. Measure the power supply voltage at right bank heated oxygen sensor (rear) and harness side connector B-02.

(1)Disconnect the connector B-02 and measure at the harness side.

(2)Turn the ignition switch to the "ON" position.





(3)Measure the voltage between terminal No. 1 and ground.

- Voltage should be battery positive voltage.
(4)Turn
the ignition switch to the "LOCK" (OFF) position.

Q. Is battery positive voltage (approximately 12 volts) present?

YES Go to Step 4.

NO Repair harness wire between the MFI relay connector A-33X (terminal No. 2) and the right bank heated oxygen sensor (rear) connector B-02 (terminal No. 1) because of open circuit or harness damage. Then go to step 6.

STEP 4.Check for open circuit to ground or harness damage between right bank heated oxygen sensor (rear) connector B-02 and 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 (terminal No. 3) and ECM connector B-10 (terminal No. 49).

- Should be less than 2 ohms.





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

- Not continuity.

Q. Is the harness wire in good condition?

YES Go to Step 5.

NO Repair it. Then go to Step 6.

STEP 5. Check the trouble symptoms.

(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2 Monitors, Trips, Drive Cycles and Readiness Codes.

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

Q. Is DTC P0037 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 6.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 6. 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 2 Monitors, Trips, Drive Cycles and Readiness Codes.

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

Q. Is DTC P0037 set?

YES Retry the troubleshooting.
NO The inspection is complete.