P0044
DTC P0044: Heated Oxygen Sensor Heater Circuit High (bank 1, sensor 3) [California]Center Exhaust Pipe Heated Oxygen Sensor Heater Circuit (Part 1):
Center Exhaust Pipe Heated Oxygen Sensor Heater Circuit (Part 2):
CIRCUIT OPERATION
- Power is supplied from the MFI relay (terminal No. 2) to the center exhaust pipe heated oxygen sensor heater.
- The ECM (terminal No. 118) controls continuity to the center exhaust pipe heated oxygen sensor 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.
DESCRIPTIONS OF MONITOR METHODS
Center exhaust pipe heated oxygen sensor heater 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 center exhaust pipe heated oxygen sensor heater is on.
- Battery positive voltage is between 11 and 16.5 volts.
Judgement Criterion
- The center exhaust pipe heated oxygen sensor heater current has continued to be higher than 10.5 ampere for 2 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 2. OBD-II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Center exhaust pipe heated oxygen sensor heater.
- ECM failed.
DIAGNOSIS
Required Special Tool:
- MB991658: Test Harness
STEP 1. Check the center exhaust pipe heated oxygen sensor.
1. Disconnect center exhaust pipe heated oxygen sensor connector D-30 and connect test harness special tool, MB991658, to the connector on the center exhaust pipe heated oxygen sensor side.
2. Measure the resistance between heated oxygen sensor connector terminal No. 1 and terminal No. 2.
Standard value: 4.5 - 8.0 ohms [at 20 °C (68 °F)]
Q: Is the measured resistance between 4.5 and 8.0 ohms [at 20 °C (68 °F)]?
YES : Go to Step 2.
NO : Replace the center exhaust pipe heated oxygen sensor. Then go to Step 3.
STEP 2. Check the trouble symptoms.
1. Carry out a test drive with the drive cycle pattern. Refer to MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 2. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0044 set?
YES : Replace the ECM. When the ECM is replaced,register the ID code. Refer to Diagnosis-ID Codes Registration Judgment Table [Vehicles with KOS] or Diagnosis-ID Codes Registration Judgment Table [Vehicles with WCM]. Then go to Step 3.
NO : It can be assumed that this malfunction is intermittent. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points-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 MFI Diagnostic Function-OBD-II Drive Cycle-Pattern 2. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0044 set?
YES : Retry the troubleshooting.
NO : The inspection is complete.