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.
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.
Related codes
Often seen with P0122
Read & clear P0122 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX