Code
P0121
Throttle
Throttle position sensor range / performance problem
The throttle position signal is not consistent with engine conditions.
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Most likely causes
- Faulty TPS
- Carbon on the throttle body
- Wiring fault
Symptoms you may notice
- Check engine light
- Poor throttle response
- Limp mode
Checks to run
- Read TPS sweep live
- Clean the throttle body
- Test sensor wiring
Tools you may need
OBD-II scanner
Multimeter
Throttle cleaner
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.