P0038
DTC P0038: Heated Oxygen Sensor Heater Control Circuit High (sensor 2)Heated Oxygen Sensor (Rear) Heater Circuit Part 1:
Heated Oxygen Sensor (Rear) Heater Circuit Part 2:
CIRCUIT OPERATION
- Power is supplied from the MFI relay (terminal No. 4) to the heated oxygen sensor (rear) heater.
- The ECM
TECHNICAL DESCRIPTION
- The ECM
DESCRIPTIONS OF MONITOR METHODS
- The heater 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)
- Engine coolant temperature sensor
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- More than 2 seconds have passed since the engine starting sequence was completed.
- While the heated oxygen sensor (front) heater is on.
- Battery positive voltage is between 11 and 16.5volts.
Judgement Criterion
- The heated oxygen sensor (rear) heater current has continued to be lower than 10.5 ampere for 2 seconds.
.OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 2 OBD-II Drive Cycle Pattern Lists
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Heated oxygen sensor (rear) heater failed.
- Connector damage
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tool:
- MB991658: Test Harness Set
STEP 1. Check the heated oxygen sensor (rear).
1. Disconnect heated oxygen sensor (rear) connector C-11 and connect test harness special tool, MB991658, to the connector on the heated oxygen (rear) sensor side.
2. Measure the resistance between heated oxygen sensor connector terminal No. 3 and terminal No. 4.
Standard value: 11 - 18 Ohms [at 20 degrees C (68 degrees F)]
Q: Is the measured resistance between 11 and 18 Ohms [at 20 degrees C (68 degrees F)]?
YES: Go to Step 2.
NO: Replace the 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 OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0038 set?
YES: Replace the ECM or PCM. Then go to Step 3.
NO: It can be assumed that this malfunction is intermittent.
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 OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0038 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.