P0121: Throttle Position Sensor A Circuit Range/Performance
Short answer: P0121 means “Throttle Position Sensor A Circuit Range/Performance”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 7 cars we cover, with a link to the full page for each car.
Standard OBD-II code Same meaning on all cars (SAE J2012).
P0121 on each car
| Car | Meaning on this car | Confidence |
|---|---|---|
| Toyota Passo (1st gen) | Throttle/Pedal Position Sensor A Range/Performance | low |
| Toyota Vitz (1st gen) | Throttle position sensor range / performance | medium |
| Toyota Corolla (11th gen, E170) | Throttle Position Sensor A Circuit Range/Performance | medium |
| Toyota Corolla (10th gen, E140) | Throttle Position Sensor A Circuit Range/Performance | medium |
| Honda City (5th gen, GM2) | Throttle Position Sensor A Circuit Range/Performance | medium |
| Honda Civic (10th gen, FC) | Throttle Position Sensor A Circuit Range/Performance | medium |
| Suzuki Wagon R (Pakistan, K10B) | Throttle Position Sensor A Circuit Range/Performance | medium |
Symptoms
- Check engine light on
Likely causes
- TPS has intermittent open or short internally
- Harness is rubbing and causing an open or short in the wiring
- Bad connection at the TPS
- Bad PCM (less likely)
- Water or corrosion in connector or sensor
What to check, in order
- Read the code and freeze-frame data with an OBD-II scanner
- Check the connector and wiring of the part named in the code
- Test the part with scanner live data or a multimeter, using the values in the repair manual
- Fix the cause, clear the code and test-drive
Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.