Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- HO2S12 and HO2S22 sensors harness circuit shorted - HO2S12 and HO2S22 sensors harness circuit connectors (wrong connection) - Faulty Engine Control Module (ECM)

Description

The heated oxygen sensor (HO2S) monitor determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank.