P0038

DTC P0038: Cylinder 1, 4 Heated Oxygen Sensor Heater (rear) Control Circuit High


















CIRCUIT OPERATION

- Power is supplied from the MFI relay (terminal No. 4) to the cylinder 1, 4 heated oxygen sensor (rear) heater.
- The ECM [M/T] or the PCM [A/T] (terminal No. 138) controls continuity to the cylinder 1, 4 heated oxygen sensor (rear) heater by turning the power transistor in the ECM [M/T] or the PCM [A/T] "ON" and "OFF".

TECHNICAL DESCRIPTION

- The ECM [M/T] or the PCM [A/T] checks whether the heater current is within a specified range when the heater is energized.

DESCRIPTIONS OF MONITOR METHODS

Cylinder 1, 4 heated oxygen sensor heater (rear) current 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)

- Engine coolant temperature sensor

DTC SET CONDITIONS

Logic Flow Chart






Check Conditions

- More than 2 seconds have passed since the engine starting sequence was completed.
- While the cylinder 1, 4 heated oxygen sensor (rear) heater is on.
- Battery positive voltage is between 11 and 16.5 volts.
Judgement Criterion

- The cylinder 1, 4 heated oxygen sensor (rear) heater current has continued to be higher than 10.5 ampere 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:)

- Cylinder 1, 4 heated oxygen sensor (rear) failed.
- Connector damage.
- ECM failed.[ M/T]
- PCM failed.[ A/T]

DIAGNOSIS

Required Special Tool:

- MD998464: Test Harness

STEP 1. Check the cylinder 1, 4 heated oxygen sensor (rear).





(1)Disconnect cylinder 1, 4 heated oxygen sensor (rear) connector B-37 and connect test harness special tool, MD998464, to the connector on the cylinder 1, 4 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).
(3)Standard value: 11 - 18ohms [at 20°C (68°F)]
Q. Is the measured resistance between 11 and 18 ohms [at 20°C (68°F)]?

YES Go to Step 2.

NO Replace the cylinder 1, 4 heated oxygen sensor (rear). Then go to Step 3.

STEP 2. 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 P0038 set?

YES Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Immobilizer System.
Then go to Step 3.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 3. 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 P0038 set?

YES Retry the troubleshooting.
NO The inspection is complete.