What are common causes for P0121?

TPS contact track worn (older potentiometer-type sensors) (high) · Carbon buildup blocking throttle plate (medium) · Corroded TPS connector (low)

What symptoms does P0121 show?

Check engine light on · Reduced throttle response, possible limp mode · Hesitation or surging · Idle too high or too low

Powertrain generic / SAE

P0121

Throttle/Pedal Position Sensor "A" Range/Performance

The throttle position sensor (TPS) signal does not match the expected range for the commanded pedal position. On drive-by-wire vehicles, two redundant sensors are compared; a divergence between them or implausible motion triggers this code.

SystemPowertrain

Typegeneric / SAE

GroupP0

Range / number1 / 21

Possible causes

TPS contact track worn (older potentiometer-type sensors) high
Carbon buildup blocking throttle plate medium
Corroded TPS connector low

Symptoms

Check engine light on
Reduced throttle response, possible limp mode
Hesitation or surging
Idle too high or too low

Inspection / repair

Difficulty: medium
DIY: possible

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Sources

References

sae:J2012