P0131 OBD Trouble Code

O2 Sensor Circuit Low Voltage

HO2S-11 Shorted to Ground (B1 S1) Conditions

ECT sensor over 170°F on previous key on, cold engine startup requirement met (ECT input less than 98°F, BTS input within 27°F of ECT input), then the test started and the PCM detected that the front Bank 1 HO2S-11 voltage was less than 56 mv for 28 seconds after engine startup

HO2S Circuit Low Voltage Conditions

Engine running in closed loop, then the PCM detected a negative HO2S voltage known as character shift downward Look for a contaminated HO2S

HO2S Circuit Low Input Conditions

Engine running in closed loop, then the PCM detected that the HO2S-11 signal that was less than 250 mv (less than 97 mv on VIN 1 & K engines), condition met for 2-4 minutes.