OBD-II Code · Sensors
P2122
Pedal Position Sensor D Low
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$150–$500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Accelerator pedal sensor D voltage low.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Limp mode
- Poor throttle response
Likely causes
- Failed pedal sensorMost common
- Wiring
Read the full diagnostic procedureP2122 is the low-voltage fault on Accelerator Pedal Position (APP) sensor D, the first of the redundant pair inside the drive-by-wire pedal assembly.
P2122 is the low-voltage fault on Accelerator Pedal Position (APP) sensor D, the first of the redundant pair inside the drive-by-wire pedal assembly. The PCM expects APP-D to sit at roughly 0.5 to 0.9V at rest and sweep to 3.8 to 4.5V at full throttle, and P2122 sets when the voltage drops below roughly 0.3V with the key on. The vehicle typically goes into reduced-power limp mode with a hard RPM cap.
Cheapest-first diagnosis
- key on engine off, scan APP-D voltage at rest, it should read 0.5 to 0.9V; press the pedal smoothly to the floor and watch for a clean linear sweep to 3.8 to 4.5V. A reading stuck at 0V or jumping to 0 mid-sweep indicates either a sensor failure or, far more commonly, a chafed or corroded harness.
- Back-probe the APP-D 5V reference, signal, and ground wires at the pedal connector, the 5V ref should hold steady at 4.9 to 5.1V regardless of pedal position.
- If the signal wire reads 0V while the 5V ref is good, the fault is between the pedal and the PCM. Inspect the harness where it enters the firewall and where it lies under the carpet on GM trucks.
- The expensive misdiagnosis is replacing the pedal assembly (typically $200 to $400) when the actual fault is a $5 length of harness repair under the carpet.
Vehicle-specific patterns1999 to 2007 GM full-size trucks (Silverado, Sierra, Tahoe, Suburban, Yukon) set P2122 from APP pedal harness corrosion where the harness runs under…
- 1999to 2007 GM full-size trucks (Silverado, Sierra, Tahoe, Suburban, Yukon) set P2122 from APP pedal harness corrosion where the harness runs under the driver-side carpet, water from boot snow soaks the foam padding and corrodes the connector pins, GM TSB 04-06-04-049 covers harness repair.
- 2003to 2009 Dodge Ram with electronic pedal sets P2122 from a failed APP sensor, internal carbon track wear.
- 2005to 2010 Ford F-150 sets P2122 from a chafed APP harness at the firewall pass-through grommet.
- 2004to 2008 Toyota Tundra 4.7L sets P2122 from internal APP sensor failure.
Estimated repair$35 to $420.
Look up another code
P2122 — frequently asked
What does a P2122 code mean?
Accelerator pedal sensor D voltage low.
What causes a P2122 code?
Common causes: Failed pedal sensor; Wiring.
What are the symptoms of a P2122 code?
Typical symptoms: Limp mode; Poor throttle response.
Is it safe to drive with a P2122 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $150-$500.
How do I diagnose a P2122 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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