P0121
PowertrainThrottle Pedalhigh severityThrottle/Pedal Position Sensor/Switch A Circuit Range/Performance
What P0121 Means
The TPS signal does not match expected values for the current operating conditions.
Symptoms
- Check Engine Light
- Erratic throttle response
- Stalling
- Hesitation
- Limp mode
Common Causes
- Worn TPS
- Carbon buildup on throttle body
- Sticking throttle plate
- Loose throttle cable
Diagnostic Steps
- Monitor TPS signal during throttle sweep
- Check for flat spots or dropouts
- Clean throttle body
- Inspect throttle cable/linkage
Where to start: Clean throttle body. Replace TPS if signal is erratic.
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