Symptoms
You probably won’t notice any driving issues since it’s not sensor number 1. You will notice the Malfunction Indicator Lamp (MIL) lighting up. In some cases, however, the engine may run rough.
Potential Causes
Causes of this DTC may include:
- Contaminated or faulty HO2S2 (sensor 3)
- HO2S2 wiring/circuit issue
- Incorrect fuel pressure
- Faulty fuel injector
- Engine coolant leak
- Faulty purge solenoid valve
- PCM failure
Diagnostic and Repair Procedures
Visually inspect the wiring and connectors for corrosion, rubbed/chafed/pinched wires, bent/loose wiring pins, burnt appearance, and/or crossed wires. Repair or replace as needed.
Check for exhaust leaks or other issues, repair if necessary.
Using a digital volt-ohmmeter (DVOM) set to ohms, check the resistance of the wiring harness connectors. Compare to manufacturer specifications. Replace or repair as needed.
If you have access to an advanced scan tool, use it to monitor the sensor readings seen by the PCM (engine running, at normal operating temperature in closed-loop mode). The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 and 1 volt; for this DTC, you will likely see the voltage “stuck” at 1V. Revving the engine should cause the sensor voltage to change (respond).
The most common fixes for this DTC appear to be either an exhaust air leak, a wiring issue with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an original one (manufacturer brand) for best results.
If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.
Other troubleshooting ideas: use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturer specifications. Inspect the purge solenoid valve. Inspect the fuel injectors. Inspect the coolant passages for leaks.