Is it safe to drive with a P0121 code?

Severity is high. Address P0121 sooner rather than later — driving with an active check engine light can worsen the problem or void emissions warranties.

How much does it cost to fix P0121?

Repair costs for P0121 typically range from $50 to $500 in the US, depending on the underlying cause. The most common fix is: Failing TPS / dirty resistive track.

What are the symptoms of P0121?

Check engine light. Hesitation or surging. Limp mode (drive-by-wire cars). Erratic idle.

Check Engine Code

P0121

Throttle Position Sensor / Switch A Circuit Range/Performance

Severity: high DIY difficulty: 2/5 Typical cost: $50–$500

Last updated April 30, 2026

What P0121 means

The throttle position signal isn't matching what the ECM expects given MAP, engine RPM, and pedal position. On drive-by-wire cars, this can trigger reduced-power mode.

Symptoms

Check engine light
Hesitation or surging
Limp mode (drive-by-wire cars)
Erratic idle

Likely causes (most common first)

Failing TPS / dirty resistive track
Carbon buildup on the throttle plate
Wiring issue
Failed throttle body

Can I keep driving?

High — risk of damage if ignored

Typical repair cost

DIY fixes can start near $50 (parts only). Shop repairs for P0121 typically run up to $500 depending on the underlying cause and vehicle. Start with the most common cause — Failing TPS / dirty resistive track — before throwing parts at it.