What P0121 means
Throttle/Petal Position Sensor/Switch A Circuit Range/Performance Problem
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 P0121:
| BMW | Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance |
| FORD | TP Sensor A Circuit Range/Performance Problem |
| MITSUBISHI | Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem; TPS(main) range |
| NISSAN | Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem |
| VOLKSWAGEN | TP Sensor Circuit Insufficient Activity |
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