What P1129 means
This is a diagnostic trouble code (DTC) reported by your vehicle's onboard OBD-II system when a specific fault is detected in the powertrain.
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 P1129:
| ACURA | MAP Higher Than Expected |
| CHRYSLER | Closed Loop Fueling Not Achieved - Bank 2; Downstream Heated Oxygen Sensor Signals Reversed |
| FORD | Downstream Heated Oxygen Sensor Signals Reversed |
| HONDA | Manifold Absolute Pressure (MAP) Sensor Circuit Higher Than Expected |
| INFINITI | MAP Higher Than Expected |
| LEXUS | Electronic Throttle Control System |
| LINCOLN | Downstream Heated Oxygen Sensor Signals Reversed |
| MAZDA | Downstream H02S Sensors Swapped |
| MERCURY | Downstream Heated Oxygen Sensor Signals Reversed |
| MITSUBISHI | Downstream Heated O2 Sensors Swapped |
| NISSAN | Downstream Heated O2 Sensors Swapped |
| OTHER | Downstream Heated O2 Sensors Swapped |
| TOYOTA | Electric Throttle Control System |
| VOLKSWAGEN | Long Term Fuel Trim mult.,Bank2 System too Rich |
Read this code on your own car
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