Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the B52 HO2S 1.
- Ignition ON, verify that the scan tool HO2S 1 parameter is between 350-500 mV.
- If greater than the specified range, test the signal circuit of the HO2S 1 for a short to the heater circuit. If the circuit/connections test normal, replace the K20 ECM.
- If all circuits/connections test normal, replace the B52 HO2S 1.