P2122: Throttle/Pedal Position Sensor D Circuit Low
Key takeaways
- P2122 means the first sensor in the accelerator pedal (sensor D) is sending a voltage lower than a working sensor can produce.
- The car usually falls back on the pedal's second sensor and limits power, so drive short trips only and stay off the highway.
- Check the pedal connector and harness first; manufacturers warn that P2122 and P2127 set just from the pedal being unplugged.
- Wiring repair runs $100–$250 and a new accelerator pedal assembly $150–$450 at a US independent shop.
- Chrysler-group bulletins tell technicians to check wiring and connectors before replacing the pedal; Ford and GM have wiring and 5-volt reference bulletins.
What P2122 means
One of the sensors in your accelerator pedal is reading lower than it ever should, so the computer treats it as a circuit fault. Scanners call it “Throttle/Pedal Position Sensor/Switch D Circuit Low.” On drive-by-wire cars the pedal has two (sometimes three) position sensors, labeled D, E and F, each with its own signal wire. The computer supplies 5 volts and a ground and reads back a signal that rises as you press the pedal. When sensor D’s signal falls below its minimum, P2122 sets. That usually means an open wire, a short to ground, or a lost 5-volt supply.
Is it safe to drive?
Short trips only. With one pedal sensor out, the computer relies on the other one and typically goes into reduced-power (limp) mode: slow response, limited speed, sometimes a flashing throttle warning. Getting to a nearby shop is usually fine. Don’t take it on the highway, because you may not be able to accelerate to merge.
The symptom that changes the answer: the engine won’t respond to the pedal or stays at idle. That means the computer has lost both sensors. Have it towed.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Loose or corroded pedal connector | Inspect and reseat the plug on the pedal; code clears and stays gone | $100–$250 |
| Chafed or pinched harness near the pedal or firewall | Continuity and short-to-ground checks; signal drops when the harness is moved | $100–$250 |
| 5-volt reference shorted by another sensor on the same circuit | Several sensor codes at once; reference recovers when the other sensor is unplugged | $100–$250 plus that sensor |
| Failed accelerator pedal assembly | Good 5 V and ground at the plug, but sensor D still reads low or drops out through the travel | $150–$450 |
| Software (some makes) | Dealer checks for a bulletin or PCM update | $100–$200, or free under warranty |
| Computer (ECM/PCM) | No reference voltage from the module with wiring proven good; rare | $800–$1,800 plus programming |
What to check first
- Read every code. P2122 alone points to sensor D’s own wire; with P2127 it’s the shared connector or supply; with codes from engine sensors too, suspect the shared 5-volt reference.
- Check the pedal connector under the dash for a loose lock, corrosion or a pushed-back pin. Wet carpet in the footwell is worth noting.
- Follow the harness from the pedal to the firewall for pinching or rubbing.
- Measure reference and ground at the pedal with the key on before buying a pedal.
- Ask about bulletins on a Ford, GM or Chrysler-group vehicle.
The bulletins lean toward wiring. Chrysler-group notes (including Ram and Alfa Romeo) tell technicians to follow the diagnostic procedure and check wiring and connectors before replacing the pedal, and warn that P2122 and P2127 set just from unplugging it. GM has preliminary information on 2019–2021 Silverado and Sierra 1500 trucks to inspect the engine harness for shorting. Ford has bulletins for 2021–2024 F-150 and 2018–2019 and 2023–2024 Super Duty trucks, and one for 2020–2021 Escape losing its voltage reference with a blown fuse.
What it costs
The cheap outcome is a reseated or cleaned pedal connector. The common outcome is a wiring or connector repair at $100–$250. The expensive outcome is a new accelerator pedal assembly at $150–$450. A diagnostic hour at $100–$180 that checks the reference and signal on the pedal plug keeps you from buying a pedal the car didn’t need. If you want help sorting the codes on your scan, ask our AI mechanic.
Related codes
P2127 is the pedal’s second sensor (E) reading low and often appears with P2122. P2138 means sensors D and E disagree. P2121 is sensor D’s range/performance code, and P2128 is sensor E reading high. A throttle body sensor code like P0122 at the same time points to a shared 5-volt supply. For hesitation, see car jerks when accelerating.
What owners report to NHTSA
34 complaints filed with NHTSA mention P2122, 28 of them since 2015, across 20 different models. The component owners most often filed it under: electrical system.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| CHEVROLET IMPALA | 8 | 2009, 2010, 2011, 2012 |
| CHEVROLET MALIBU | 4 | 2016, 2017 |
| JEEP RENEGADE | 3 | 2017, 2019, 2020 |
Manufacturer service bulletins that name P2122
51 technical service bulletins and manufacturer communications filed with NHTSA mention P2122, from 15 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- CHRYSLER POWER TRAIN, bulletin 10173281: PEDAL, Accelerator Before replacing accelerator pedal, be sure to follow fault code diagnostic procedures in Service Library and be sure to check wiring and connectors. P2122 and P2127 will set if accelerator pedal conne…
- FORD F-600 SD (2023, 2024), bulletin 10253556: Some 2023-2024 F-Super Duty vehicles may exhibit an illuminated powertrain malfunction (wrench) indicator with diagnostic trouble codes (DTC) P2122, P2123, P2127, P2128, and/or P2138 stored in the powertrain control modu…
- FORD F-150 (2021, 2022, 2023, 2024), bulletin 11008946: Some 2021-2024 F-150 non-Lightning vehicles may exhibit an illuminated powertrain malfunction (wrench) indicator with diagnostic trouble codes (DTCs) P2122, P2123, P2127, P2128, and/or P2138 stored in the powertrain cont…
- CHEVROLET SILVERADO 1500 (2019, 2020, 2021), bulletin 10193465: This Preliminary information communicates the following issues and directs dealership to inspect the engine harness for shorting. Some customers may comment on any of the following concerns: - SES MIL - No Start - No Cra…
- GMC SIERRA 1500 (2019, 2020, 2021), bulletin 10193465: This Preliminary information communicates the following issues and directs dealership to inspect the engine harness for shorting. Some customers may comment on any of the following concerns: - SES MIL - No Start - No Cra…
- FORD ESCAPE (2020, 2021), bulletin 10201593: Some 2020-2021 Escape vehicles may exhibit a loss of voltage reference (VREF) or runs rough, blow fuse 44 and may or may not set DTC's P06A7,P0840,P0842,P0845,P0847,P2122,P2127,P0522,P008A,P06A6,P2196,P0192, P0212,P0340,…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Where is the P2122 sensor?
In the accelerator pedal. On drive-by-wire cars the pedal is an assembly with two or three position sensors built in, and a connector on the back of it under the dash.
Can I drive with P2122?
Short trips, usually. The computer uses the pedal's other sensor and limits power, so acceleration is slow and speed is capped. Stay off the highway, and have it towed if the car won't respond to the pedal.
Why do P2122 and P2127 show up together?
They're the two sensors in the same pedal, sharing a connector and often a 5-volt supply. Both low at once points to the connector, the supply or the harness rather than two failed sensors.
Can I replace the accelerator pedal myself?
On many cars it's a few bolts and one connector under the dash. Check the connector and wiring first, since a new pedal won't fix a chafed wire, and some cars need a relearn afterward.