Code No. P0038: Right Bank Oxygen Sensor (rear) Heater Circuit High Input

OPERATION

Power is supplied to the heater power terminal of the right bank oxygen sensor (rear) connector from the engine control relay.
The heater of the right bank oxygen sensor (rear) connector is controlled by the power transistor in the engine-ECU connector terminal OHRR.

FUNCTION

The power supply to the right bank oxygen sensor (rear) heater is controlled by the ON/OFF control of the power transistor in the engine-ECU.
Heating the right bank oxygen sensor (rear) heater enables the right bank oxygen sensor (rear) to provide good response even when the exhaust emission temperature is low.

TROUBLE JUDGEMENT

Check Conditions

More than 2 seconds have passed since the engine starting sequence was completed.
While the right bank oxygen sensor (rear) heater is on.
Battery positive voltage is more than 11 V and is less than 16.5 V.

Judgement Criterion

The right bank oxygen sensor (rear) heater current is more than 10.5 A for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

None

PROBABLE CAUSES

Failed right bank oxygen sensor (rear) heater
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check right bank oxygen sensor (rear) itself.

Right bank oxygen sensor (rear) check (Refer to ).

Q. Is the check result normal?

	Go to Step 2.

	Replace the right bank oxygen sensor (rear).

STEP 2. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is diagnosis code set?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).