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DTC P0038-00: Oxygen Sensor (rear) Heater circuit high input
 
 
 
 
CIRCUIT OPERATION
  • MFI relay is built into the IPDM E/R.
  • Power is supplied to the heater power terminal of the heated oxygen sensor (rear) connector terminal number 2 from the MFI relay connector terminal.
  • The heater of the heated oxygen sensor (rear) is controlled by the power transistor in the ECM connector terminal number 2.
 
 
TECHNICAL DESCRIPTION
The ECM checks whether the heater current is within a specified range when the heater is energized.
 
 
DESCRIPTIONS OF MONITOR METHODS
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 set in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
  • More than 2 seconds have passed since the power supply mode of the electric motor switch was ON.
  • While the heated oxygen sensor (rear) heater is on.
  • 12V battery positive voltage is between 11.0 and 16.5 volts.
Judgment Criterion
  • The heated oxygen sensor (rear) heater current has continued to be higher than average 10.5 amperes for 2 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
None.
 
 
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function, OBD-II Drive Cycle – Pattern 1 OBD- II DRIVE CYCLE.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Shorted heated oxygen sensor (rear) heater circuit or connector damage.
  • Heated oxygen sensor (rear) failed.
  • ECM failed.
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
1.STEP 1. Check heated oxygen sensor (rear) itself.
Check heated oxygen sensor (rear) itself (Refer to HEATED OXYGEN SENSOR CHECK).
Q: Is the check result normal?
Replace the heated oxygen sensor (rear) (Refer to ENGINE, Engine, Motor and Emission Control – Emission Control – Exhaust Gas Purification System CATALYTIC CONVERTER REMOVAL AND INSTALLATION).
 
2.STEP 2. Check harness between heated oxygen sensor (rear) connector terminal number 2 and IPDM E/R connector terminal number 75.
Check power supply line for short circuit.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
3.STEP 3. Check harness between heated oxygen sensor (rear) connector terminal number 1 and ECM connector terminal number 2.
Check ground line for short circuit.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
4.STEP 4. Test the OBD-II drive cycle.
After erasing the DTC, carry out test drive with the drive cycle pattern, and recheck the DTC.
(1) Use scan tool (M.U.T.-III SE) to erase the DTC.
(2) Carry out test drive with the drive cycle pattern (Refer to Diagnostic Function, OBD-II Drive Cycle – Pattern 1 OBD- II DRIVE CYCLE).
(3) Use scan tool (M.U.T.-III SE) to recheck the DTC.
Q: Is DTC P0038-00 set?
Replace the ECM (Refer to ENGINE CONTROL MODULE (ECM) REMOVAL AND INSTALLATION).
Intermittent malfunction (Refer to GENERAL INFORMATION, General Information – How to Use Troubleshooting/Inspection Service Points – How to Cope with Intermittent Malfunctions HOW TO COPE WITH INTERMITTENT MALFUNCTIONS).