P0053

DTC P0053: Heated Oxygen Sensor (front) Heater Resistance






















CIRCUIT OPERATION

- Power is supplied from the MFI relay (terminal No. 2) to the heated oxygen sensor (front) heater.
- The ECM (terminal No. 34) controls continuity to the heated oxygen sensor (front) 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

Heated oxygen sensor (front) heater 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)

- Not applicable

DTC SET CONDITIONS

Logic Flow Chart






Check Conditions

- More than 60 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 16.5 volts.
- Intake air temperature is more than -10°C (14°F).
- On duty cycle of the heated oxygen sensor (front) heater is between 3 and 97 percent.
Judgement Criterion

- The heated oxygen sensor (front) heater current has continued to be lower than average 0.6 ampere for 10 seconds.

FAIL-SAFE AND BACKUP FUNCTION

- None

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:)

- Heated oxygen sensor (front) heater circuit harness damage or connector damage.
- Heated oxygen sensor (front) heater failed.
- ECM failed.


DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991658: Test Harness

STEP 1. Check harness connector C-34 at heated oxygen sensor
(front) for damage.

Q. Is the harness connector in good condition?

YES Go to Step 2.
NO Repair or replace it. Harness Connector Inspection.
Then go to Step 8.
STEP 2. Check the heated oxygen sensor (front).

(1)Disconnect heated oxygen sensor (front) connector C-34 and connect test harness special tool, MB991658, to the connector on the heated oxygen sensor (front) side.





(2)Measure the resistance between heated oxygen sensor connector terminal No. 1 and terminal No. 2.
Standard value: 4.5 - 8.0ohms [at 20°C (68°F)]

Q. Is the measured resistance between 4.5 and 8.0ohms [at 20°C (68°F)]?

YES Go to Step 3.

NO Replace the heated oxygen sensor (front). Then go to Step 8.

STEP 3. Check harness connector A-34X at MFI relay for damage.

Q. Is the harness connector in good condition?

YES Go to Step 4.
NO Repair or replace it. Harness Connector Inspection.
Then go to Step 8.
STEP 4. Check for harness damage between MFI relay connector A-34X (terminal No. 2) and heated oxygen sensor (front) connector C-34 (terminal No. 1).

Q. Is the harness wire in good condition?

YES Go to Step 5.
NO Repair it. Then go to Step 8.
STEP 5. Check harness connector B-09 at ECM for damage.

Q. Is the harness connector in good condition?

YES Go to Step 6.
NO Repair or replace it. Harness Connector Inspection.
Then go to Step 8.
STEP 6. Check for harness damage between heated oxygen sensor (front) connector C-34 (terminal No. 2) and ECM connector B-09 (terminal No. 34).

NOTE:
Check harness after checking intermediate connector A-13. If intermediate connector is damaged, repair or replace it. Harness Connector Inspection. Then go to Step 8.

Q. Is the harness wire in good condition?

YES Go to Step 7.
NO Repair it. Then go to Step 8.
STEP 7. 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 P0053 set?

YES Replace the ECM (Refer to, Removal and Installation Removal and Replacement).
Then go to Step 8.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 8. 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 P0053 set?

YES Retry the troubleshooting.
NO The inspection is complete.