Checking Components
Check the exhaust system for air leakage.
Check the cable for a short-circuit to supply voltage or ground.
Check between:
- The cable between engine control module (ECM) terminal #A44 (#A44) and heated oxygen sensor (HO2S) terminal #5
- The cable for pump current between engine control module (ECM) terminal #A25 (#A25) and heated oxygen sensor (HO2S) terminal #6
- The cable for calibration current between engine control module (ECM) terminal #A69 (#B9) and heated oxygen sensor (HO2S) terminal #2.
Check the cable between engine control module (ECM) terminal #A43 (#A43) and heated oxygen sensor (HO2S) terminal #1. Check for an open-circuit.
HINT: If the above fault-tracing does not remedy the fault, try replacing the heated oxygen sensors (HO2S), as the diagnostic trouble code (DTC) can also be stored by a damaged front/rear heated oxygen sensor (HO2S).
Remedy as necessary.
Other information
- see CHECKING FOR AIR LEAKAGE IN THE EXHAUST SYSTEM
- For B5xx4T, see HEATED OXYGEN SENSOR (HO2S), REPLACING
- For B6xx4T, see HEATED OXYGEN SENSOR (HO2S), REPLACING .
- see CHECKING WIRING AND TERMINALS
- Continue
Refer to VERIFICATION