DTC P0131: Heated Oxygen Sensor No. 1 Circuit Low Input, Or DTC P0132: Heated Oxygen Sensor No. 1 Circuit High Input: Condition

DTC is set when HO2S No. 1 output voltage does not vary from less than 0.3 volt to more than 0.6 volt when vehicle is operating after reaching normal operating temperature. This circuit is monitored once per drive cycle. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• HO2S No. 1 malfunction.
• Open circuit between HO2S No. 1 and PCM.