P0122 Throttle/Pedal Position Sensor/Switch A Circuit Low Input

P0122 indicates a low input from throttle or pedal position sensor/switch A. The module sees the sensor voltage lower than expected.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not adjust throttle stops to compensate for a low signal; modern throttle systems need circuit diagnosis and relearn procedures.

Symptoms of P0122

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0122

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Check sensor reference voltage, ground, signal return, connector terminals, and harness damage.
Compare sensor A to redundant throttle or pedal channels to see whether only one circuit is low.
Watch live data while gently moving the harness and throttle to expose intermittent low-signal drops.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.