Signal Too Low. Intermittent Fault

Checking Wiring And Connections
- Check cable between heated oxygen sensor (HO2S) terminal 1 and main relay (2/32) terminal 3 for an intermittent open-circuit.
- Check cable between heated oxygen sensor terminal 2 and engine control module (ECM) # A14 (for diagnostic trouble code (DTC) EFI-521)/ # A29 (for diagnostic trouble code EFI-522) for an intermittent short-circuit to ground or an intermittent open-circuit.
- Check heated oxygen sensor and engine control module connectors for loose connections, contact resistance and oxidation.

CAUTION: Do not apply rust solvent spray or grease to the heated oxygen sensor connector.

Fault-tracing Information
- For intermittent faults fault-tracing is not followed by a verification because the fault is not present at this moment.
- Do you want to repeat fault-tracing?

Yes:
^ Return to Checking Wiring And Connections section above.

No:
^ Operation done