Possible Causes
WARNING: This page is about a different car, the 2003 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
DTC will set when AF+ voltage remains 4.5 volts or more for 5 seconds or more, or when AF+ voltage remains 0.5 volt or less for 5 seconds or more. Also, when AF+ minus AF- is 0.1 volt or less for 5 seconds or more, or when AF+ minus AF- is 0.8 volt or more for 5 seconds or more. Possible causes are:
- Open or short in A/F sensor circuit.
- Defective A/F sensor.
- A/F sensor heater and relay circuit.
- Defective A/F sensor heater relay.
- Defective ECM.