DTC P0031: Ho2S Heater (Front) Circuit Low: Condition

DTC is set when PCM detects low input voltage from ground side of front HO2S heater circuit after PCM turns HO2S heater circuit off. This is an intermittent monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• Front HO2S malfunction.
• Loose connection at connectors.
• Open circuit between front HO2S and ignition switch.
• Open or short circuit between front HO2S and PCM.
• PCM malfunction.