Diesel Data: Automotive Repair

Diagnostic Trouble Code (DTC) Information







Diagnostic trouble code (DTC) information

Condition




The engine control module (ECM) checks the rear heated oxygen sensor (HO2S) signal (bank 1). The Engine control module (ECM) actively regulates between rich and lean fuel/air mixture and registers how well the rear heated oxygen sensor (HO2S) signal follows these changes.
The diagnostic trouble code (DTC) is stored if the control module detects that:
- The heated oxygen sensor reacts too slowly at switch from rich to lean.
The control module's test for the diagnostic trouble code (DTC) starts in the event of:
- Special driving cases with fuel shut-offs.

Note! The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met.

Substitute value
- None.

Possible source
- Contact resistance or oxidation in the terminals.
- Damaged rear heated oxygen sensor (HO2S).

Fault symptom[s]
- Warning lights and chimes/Malfunction Indicator Light ("Check engine" light) indication/no indication