P2123 code meaning
Throttle/Pedal Position Sensor/Switch D Circuit High
Powertrain system Generic code P21xx codes Check engine light
What P2123 means
P2123 is the high-voltage fault on pedal track D, usually an open sensor ground or a short to the 5 V reference or to battery voltage. GM's 2007 tables set it above 4.75 V (19 of 39 counts, Type A), a Bosch-based GM ECM from 2012 above 4.824 V lasting 0.2 s, and the 2014 VW Touareg above 4.89 V; Ford uses 4.75 V. A track pinned near the supply rail would read like a fully pressed pedal, so the controller rejects it, carries on with track E and caps engine output. GM PIP3783D lists the code among the very intermittent pedal faults on 2007-2014 full-size trucks and advises wiggling the harness and testing terminal tension. P2122 is the low counterpart, P2120 the general circuit code, P2128 the high fault on track E.
P2123 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2123
- Engine warning lamp and reduced power message
- Limited throttle opening despite full pedal
- Fault may appear and vanish with harness movement
Common causes of P2123
- Most likelyOpen or high-resistance ground return of the pedal sensor
- PossibleTrack D signal shorted to the 5 V reference or battery voltage
- PossibleInternal pedal sensor fault
- Less likelyLoose or spread terminals at pedal or inline connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Accelerator pedal position sensorPedal sensor wiringECM
What each part of P2123 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 1 | Area: fuel and air metering. |
| 23 | The exact fault in that area. |
What to do next
- Note P2123 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2123
What does P2123 mean?
P2123 means "Throttle/Pedal Position Sensor/Switch D Circuit High". P2123 is the high-voltage fault on pedal track D, usually an open sensor ground or a short to the 5 V reference or to battery voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P2123?
Drive gently and only to a workshop. With P2123 the car can go into limp mode (reduced power) to protect itself.
Will P2123 fail an emissions test?
Yes, it can. P2123 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2123 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2123 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.