What P1131 means
Lack Of HO2S Switch - Sensor Indicates Lean
Common causes (general)
Before spending money on parts, verify the code with a scan tool and read freeze frame data. Freeze frame captures every sensor value at the moment the code set — this is often enough to figure out the root cause without further testing.
Manufacturer-specific descriptions
Different manufacturers use this code for slightly different failure modes. Here's what your specific make means by P1131:
| BMW | HO2S 2 Bank 2 Dynamic Test Failure |
| BUICK | HO2S Circuit Low Variance Bank 1 Sensor 2 |
| CADILLAC | HO2S Circuit Low Variance Bank 1 Sensor 2 |
| CHEVY | HO2S Circuit Low Variance Bank 1 Sensor 2 |
| CHRYSLER | Fuel Pressure Regulator Valve; Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank 1 |
| FIAT | Lambda sensor signal (drift or sensor signal circuit open)Plausibility 2 |
| FORD | Lack Of HO2S11 Switch - Sensor Indicates Lean; Lack Of HO2S Switch - Sensor Indicates Lean |
| GM | HO2S Circuit Low Variance Bank 1 Sensor 2 - Read Our Article On Oxygen Sensor Codes For Help With These GM Trouble Codes; Heated Oxygen Sensor (HO2S) Circuit Low Variance Bank 1 Sensor 2 |
| GMC | HO2S Circuit Low Variance Bank 1 Sensor 2 |
| LINCOLN | Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 1 |
| MAZDA | HO2S Bank 1 Sensor 1 Signal Below 0.45v AF Ratio Too Lean |
| MERCURY | Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 1 |
| MITSUBISHI | Lack Of HO2S Switch - Sensor Indicates Lean |
| NISSAN | Lack Of HO2S Switch - Sensor Indicates Lean; Swirl Control Solenoid Valve |
| OLDSMOBILE | HO2S Circuit Low Variance Bank 1 Sensor 2 |
| OTHER | Lack Of HO2S Switch - Sensor Indicates Lean |
| SATURN | HO2S Circuit Low Variance Bank 1 Sensor 2 |
| SUBARU | Front Oxygen Sensor Circuit Malfunction Short Circuit |
| VOLKSWAGEN | HO2S Circuit Low Variance Bank 1 Sensor 2; Bank2 - Sensor1 Internal Rsistance too High |
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