H15 - Check HO2S On Engines With MAP Sensors

NOTE: Vacuum/air leaks in non-Electronic Engine Controls (EEC) areas could also cause Diagnostic Trouble Codes (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.

- Lead contaminated Heated Oxygen Sensor (HO2S).

- Key "OFF".

- Verify Manifold Absolute Pressure (MAP) sensor output voltage (refer to procedure in pinpoint test step DF3). DF3

- Disconnect appropriate HO2S from vehicle harness.

- Connect to HO2S circuit and HO2S GND or SIG RTN at the HO2S connector.

- Disconnect and plug vacuum line at MAP sensor.

- Digital Volt/Ohm Meter (DVOM) on 20 volt scale.

- Start engine and apply 33-46 kPa (10-14 in Hg) to MAP sensor.

- Run engine at approximately 2000 rpm for two minutes.

- Does the DVOM indicate greater than 0.5 volt within two minutes?

Yes -- Go to H17. H17 - Check Continuity of HO2S Signal and HO2S Ground

No -- Replace HO2S. Reconnect MAP sensor vacuum line. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)