Diagnostic Procedures
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
- Start and allow engine idle to stabilize for about one minute. Ensure engine is at normal operating temperature. Using scan tool, monitor HO2S heater current. If HO2S heater current is 0.45-0.65 amp, see DIAGNOSTIC AIDS . If HO2S heater current is not 0.45-0.65 amp, go to next step.
- Check fuse for HO2S 1 ignition feed circuit. If fuse is open, go to step 11. If fuse is not open, go to next step.
- Turn ignition on, with engine off. Disconnect HO2S 1 harness connector. Using a test light connected to a known-good chassis ground, probe ignition feed circuit at HO2S 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 7.
- Connect test light between HO2S 1 ignition feed and heater ground circuit. Start engine. If test light illuminates, go to step 9. If test light does not illuminate, go to next step.
- Turn ignition off. Disconnect PCM harness connector. Check resistance of HO2S heater control circuit between PCM and HO2S harness connector. If resistance is 0-5 ohms, go to step 12. If resistance is not 0-5 ohms, go to step 8.
- Repair open in HO2S 1 ignition feed circuit to HO2S 1. After repairs, go to step 14.
- Repair open or high resistance in HO2S 1 heater control circuit. After repairs, go to step 14.
- Check for poor connections or terminal tension at HO2S 1. Repair as necessary. After repairs, go to step 14. If connections or terminal tension are okay, go to next step.
- Replace HO2S 1. After replacing sensor, go to step 14.
- Locate and repair short to ground in HO2S 1 ignition feed circuit. Replace fuse. After repairs, go to step 14.
- Check for poor connections or terminal tension at PCM. Repair as necessary. After repairs, go to step 14. If connections or terminal tensions are okay, go to next step.
- Replace PCM. Perform PCM reprogramming procedures. After repairs, go to next step.
- Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate under conditions required to duplicate DTC. See CIRCUIT DESCRIPTION . Using scan tool, check for DTCs. If this DTC resets, go to step 2. If this DTC does not reset, system is okay.