H16 - Check HO2S On Engines With MAF Sensor
NOTE: The purpose of this test is to verify the Heated Oxygen Sensor (HO2S) can generate greater than 0.5 volt during Engine Running Self-Test.
Any vacuum/air leaks in non-Electronic Engine Controls (EEC) areas could also cause Diagnostic Trouble Code (DTC) 136,172 or 176. Check for:
- Leaking vacuum actuator (e.g. A/C control motor).
- Engine sealing.
- Exhaust Gas Recirculation (EGR) system.
- Positive Crankcase Ventilation (PCV) system.
- Unmetered air leak between Mass Air Flow (MAF) sensor and throttle body.
- Lead contaminated HO2S.
- Key "OFF".
- Disconnect appropriate HO2S from vehicle harness.
- Connect Digital Volt/Ohm Meter (DVOM) to HO2S circuit and HO2S SIG RTN or HO2S GND at the HO2S connector.
- DVOM on 20 volt scale.
- Run engine at approximately 2000 rpm for two minutes.
- Rerun Engine Running Self-Test and monitor HO2S voltage. Key ON Engine Running (KOER) Self-Test
- Does DVOM indicate greater than 0.5 volt at the end of Self-Test?
Yes -- Go to H17. H17 - Check Continuity of HO2S Signal and HO2S Ground
No -- Replace HO2S. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)