P0121: Throttle / Pedal Position Sensor Circuit Range/Performance
P0121 often starts with a dirty throttle body. Cleaning is a solid first attempt before replacing the sensor.
Severity: moderate · System: Powertrain · Safe to drive: usually, short-term. Have it looked at soon — can trigger limp mode without warning.
Symptoms
- Erratic idle
- Hesitation
- Limp mode
- Sudden power loss
Common causes
- Dirty throttle body
- Failed TPS
- Wiring problem
Fair repair prices
| Throttle body cleaning | $80–$200 |
|---|---|
| Throttle position sensor | $150–$400 |
| Throttle body replacement | $400–$900 |
Ranges are US market averages (parts and labor). If your shop's quote is above the high end, ask for a line-item breakdown or run it through the invoice checker.
Other codes
- P0300 — Random / Multiple Cylinder Misfire Detected
- P0301 — Cylinder 1 Misfire Detected
- P0420 — Catalyst System Efficiency Below Threshold (Bank 1)
- P0430 — Catalyst System Efficiency Below Threshold (Bank 2)
- P0171 — System Too Lean (Bank 1)
- P0174 — System Too Lean (Bank 2)
- P0442 — Evaporative Emission Control System Leak (Small)
- P0455 — Evaporative Emission Control System Leak (Large)