P0122

Throttle/Pedal Position Sensor/Switch A Circuit Low

Throttle / air metering Generic OBD-II High

What it means

P0122 means the ECM sees an abnormally low voltage from the throttle (or accelerator pedal) position sensor "A" circuit. Because the module relies on this signal to know how far the throttle is open, a low or lost signal often triggers reduced-power limp mode, hesitation, and rough idle. The usual cause is damaged wiring, a bad connector, or a failed sensor.

High

Can I keep driving? Risky — the fault often forces the vehicle into a reduced-power limp mode with poor throttle response, so drive gently and have it checked soon.

Real-world scan data

Seen in

4,557

scans in the past year

Found in

0.7%

of scans

1.3%

of scans that found faults

Appears alongside · share of P0122 scans

P0222in 51.9% of scans

P0113in 14.4% of scans

P0123in 12.2% 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 power or limp mode
Poor or unresponsive throttle response and hesitation
Erratic, high, or surging idle
Occasional stalling

Common causes

Most likely first

Damaged wiring or a signal wire shorted to ground (most common cause of a low reading)Likely
Loose or corroded connector at the throttle position sensorCommon
Faulty throttle position sensorCommon
Loss of the 5-volt reference or ground to the sensorLess often
Faulty ECM (rare)Less often

How to diagnose & fix

Work through it in order

Inspect the sensor connector and wiring for damage, corrosion, or a pinched harness.
Backprobe the signal wire and check for the expected voltage rising smoothly as the throttle opens.
Verify the 5-volt reference and ground are present at the connector.
If wiring and references are good, replace the throttle position sensor.
Only consider the ECM after wiring, connector, and sensor test good. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0122?+

Only carefully and briefly. The car may drop into limp mode with limited power, which is unsafe in traffic — get it diagnosed before relying on it.

Can I just clear P0122?+

It will return as soon as the sensor sees the low signal again. The wiring or sensor fault has to be repaired first.

Read & clear P0122 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