One track of the accelerator pedal sensor is reading high. The pedal has two independent tracks precisely so the ECU can spot this.
P2123 — also written P2123, P 2123, 2123 — is the OBD-II code for throttle/pedal position sensor 'd' circuit high. Same code, same fix: this page covers every spelling of it.
P2123 is a engine fault code, typically costing £90–£400 to put right in a UK garage.
What causes P2123?
- Failed accelerator pedal sensor
- Water ingress into the pedal connector
- Chafed wiring in the footwell
- Spilt drink into the pedal assembly
How P2123 is fixed
- Compare both pedal tracks on live data
- Replace the accelerator pedal assembly
- Dry and repair the connector
P2123 repair cost in the UK
Most P2123 repairs land between £90–£400 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Can you drive with P2123?
Limp mode. Do not drive far with an unreliable pedal signal.
Urgency: high.