P0120

Throttle/Pedal Position Sensor/Switch A Circuit

Throttle / pedal position Generic OBD-II High

What it means

P0120 means the ECM has detected a problem in the "A" throttle or accelerator-pedal position sensor circuit. This sensor tells the ECM how far the throttle or pedal is open, so a fault directly affects power delivery — commonly triggering reduced-power limp mode, erratic idle, hesitation, or stalling. It's worth diagnosing promptly because it affects how the vehicle responds to the pedal.

High

Can I keep driving? Drive with caution — the vehicle may drop into reduced-power (limp) mode, idle erratically, or stall; have it addressed promptly.

Real-world scan data

Seen in

1,780

scans in the past year

Found in

0.3%

of scans

0.5%

of scans that found faults

Appears alongside · share of P0120 scans

P0220in 43.7% of scans

P0110in 14.7% of scans

P0645in 14.3% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Reduced or limited power (limp mode)
Hesitation, surging, or poor acceleration
Erratic idle or stalling

Common causes

Most likely first

Faulty throttle/pedal position sensor 'A'Likely
Damaged, chafed, or shorted wiring in the sensor circuitCommon
Loose or corroded connector at the sensorCommon
Failed ECM/PCM (rare)Less often

How to diagnose & fix

Work through it in order

Watch the throttle and pedal position values in live data while sweeping the pedal — look for dropouts, spikes, or a flat line.
Inspect the sensor connector and harness for damage, corrosion, or loose pins.
Check the sensor's reference voltage and ground, and test the signal voltage sweep against spec.
Replace the throttle/pedal position sensor if the signal is faulty. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0120?+

Only carefully. Throttle position faults often trigger limp mode or cause stalling and surging, which can be unsafe in traffic. Get it diagnosed before relying on the vehicle.

Can I just clear P0120?+

It will return quickly if the sensor or wiring is faulty, and the drivability and limp-mode issues come back with it. Fix the root cause first.

Read & clear P0120 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX