Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition on, engine off. Disconnect HO2S bank 1 sensor 1 and HO2S bank 1 sensor 2 harness connectors. Using scan tool, monitor HO2S bank 1 sensor 1 and HO2S bank 1 sensor 2. If both readings are 400-538 mV, go to step 3 . If both readings are not 400-538 mV, go to next step.
- If voltage is less than 400 mV on a sensor, see DTC P0131: HO2S CIRCUIT - LOW VOLTAGE - BANK 1, SENSOR 1 for sensor 1, or DTC P0137: HO2S CIRCUIT - LOW VOLTAGE - BANK 1 SENSOR 2 for sensor 2. If voltage is greater than 538 mV on a sensor, see DTC P0132: HO2S CIRCUIT - HIGH VOLTAGE - BANK 1, SENSOR 1 for sensor 1 or DTC P0138: HO2S CIRCUIT - HIGH VOLTAGE - BANK 1 SENSOR 2 for sensor 2.
- Connect test light between battery voltage and HO2S bank 1 sensor 1 connector terminal No. 2 (Light Blue wire). Using scan tool, monitor HO2S bank 1 sensor 1. If reading is more than 538 mV, repair short between Light Blue wire and Purple/white wire. If reading is not more than 538 mV, ensure no exhaust leaks exist between the HO2S bank 1 sensor 1 and 18 inches after the HO2S bank 1 sensor 2. An exhaust leak in that area will cause false HO2S bank 1 sensor 2 readings and may set DTC P0130. Repair a leak if one exists. The only other possibility is a contaminated or weak HO2S bank 1 sensor 1. Repair source of contamination (fuel, oil, sealant or coolant) if contaminated. Replace the HO2S bank 1 sensor l.