OBD codes / P2122
P2122
ModeratePedal Position Sensor/Switch D Circuit Low
Usually drivable to a shop in reduced-power mode, but the pedal may respond poorly or not at all, so avoid situations that demand quick acceleration. If the car will only idle, have it towed rather than creeping through traffic.
What this code means
Drive-by-wire cars have no throttle cable — the accelerator pedal contains two (sometimes three) position sensors, and the computer compares them constantly. P2122 means the signal from pedal sensor D is stuck below its valid range, essentially reading 'less than zero throttle.' That points to an electrical problem: an open signal wire, a lost 5-volt reference, a dirty or corroded connector at the pedal, or a failed sensor inside the pedal assembly. Because the redundant sensor no longer agrees, most cars respond with reduced-power mode, and some will ignore the pedal entirely and idle only. The pedal sensors are almost always built into the pedal assembly, which is usually a simple unbolt-and-plug replacement — but check the connector first, since that's the cheap and common fix.
Symptoms you might notice
- Reduced-power or 'limp' mode
- Pedal that feels dead or unresponsive
- Car may only idle regardless of pedal input
- Intermittent hesitation or power loss
- Check-engine light
What it costs to fix
Typical range: $40–$450 · about ~0.3–1 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Connector cleaning / minor wiring repair | $5–$80 | ~0.3–1 hrs |
| Accelerator pedal assembly | $80–$300 | ~0.3–1 hrs |
The pedal assembly is one of the easier drive-by-wire parts to replace — typically a few bolts and one connector under the dash — so labor stays low. The spread is mostly in the part price, and a connector cleaning sometimes fixes it for nearly nothing.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P2122 for my exact vehicle →
Frequently asked
Why does my gas pedal feel dead with P2122?
The computer only opens the throttle when both pedal sensors agree on what your foot is doing. With sensor D reading below its valid range, the computer stops trusting the pedal and limits or ignores it — that's the dead-pedal feeling.
Is P2122 the pedal or the wiring?
Both are common. A corroded or loose connector at the pedal produces exactly this code and costs almost nothing to fix, so inspect and clean it first. If the connector and wiring check out, the sensor inside the pedal assembly has likely failed.
Can I replace just the sensor instead of the whole pedal?
On nearly all vehicles, no — the sensors are sealed inside the pedal assembly and it's replaced as one unit. Fortunately it's usually an inexpensive, quick job compared to most drive-by-wire repairs.
What's the difference between P2122 and P2127?
Same fault, different sensor: P2122 is pedal sensor D reading too low, P2127 is pedal sensor E reading too low. D and E are the two redundant sensors in the same pedal assembly, so the diagnosis and repair are essentially identical.
Seeing P2122 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P2122 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P2122 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.