Trouble Code Conditions
4-4-3 THREE-WAY CATALYTIC CONVERTER EFFICIENCYTrouble Code Conditions
- The engine control module (ECM) continuously monitors three-way catalytic converter (TWC) efficiency by comparing the signal from the rear heated oxygen sensor (HO2S) with the signal from the front heated oxygen sensor. When three-way catalytic converter efficiency deviates too much the engine control module stores diagnostic trouble code (DTC) EFI-443.
Substitute value(s)
- None.
Possible source(s)
- Uneven compression.
- Air leakage in the intake system.
- Air leakage in the exhaust system.
- Faulty fuel pressure.
- Defective three-way catalytic converter.
Fault symptom(s)
- May result in poor performance.
Other Diagnostic Trouble Codes
- Read off other diagnostic trouble codes (DTCs).
If any misfire-related diagnostic trouble code is stored:
^ Select Alternative 1.
If diagnostic trouble code EFI-435 is stored:
^ Select Alternative 2.
If diagnostic trouble code EFI-436 is stored:
^ Select Alternative 3.
If none of the above diagnostic trouble codes have been stored:
^ Select Alternative 4.
Select an Alternative.
- Select one of the following options to continue.
Alternative 1:
^ Code EFI-45X, EFI-543, EFI-545, EFI-55X Misfire Cylinder X.
Alternative 2:
^ Code EFI-435 Front Heated Oxygen Sensor Too Slow.
Alternative 3:
^ Code EFI-436 Rear Heated Oxygen Sensor Compensation.
Alternative 4:
^ Proceed to Status Messages section below.
Status Message
- Proceed to Faulty Signal: