P2122
Throttle/Pedal Position Sensor/Switch D Circuit Low Input
When a vehicle powertrain module registers the fault code P2122, it points directly to an internal system malfunction identified as "Throttle/Pedal Position Sensor/Switch D Circuit Low Input". Operating your engine under this condition may degrade long-term fuel maps.
Driver's Summary
Storing code P2122 is your car's way of telling you something is wrong with the throttle/pedal position sensor/switch d circuit low input. In practice, this fault causes lack of engine response when pressing the gas pedal. This is not a code to ignore — the underlying fault can rapidly worsen and lead to costly repairs if driving continues.
Symptoms
Lack of engine response when pressing the gas pedal
Common Causes
- Short to ground in pedal sensor wiring
- Failed Accelerator Pedal Position (APP) sensor
- Water in the floorboard corroding connector
- Failed PCM
How to Fix
- 1 Repair shorted wire
- 2 Replace accelerator pedal assembly
- 3 Dry out carpet and clean connector
- 4 Test PCM reference voltage
Technical Explanation
The ECM detects code P2122 by continuously monitoring the relevant sensor circuit against calibrated threshold values stored in its non-volatile memory. The control module samples the circuit continuously during normal operation, using both voltage level monitoring and frequency analysis to detect open circuits, shorts to ground, shorts to battery voltage, and high-resistance connections. The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
With P2122 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to short to ground in pedal sensor wiring.
Mechanic's Pro Tip
The most common mistake with P2122 is replacing the sensor without verifying the reference voltage and ground integrity first. Use a scan tool to monitor the sensor's live output; a truly failed sensor shows a stuck, flatlined reading — a sensor that fluctuates but reads slightly off usually indicates a wiring or vacuum issue, not a dead sensor. Always spray electrical contact cleaner on the connector pins before condemning the sensor.
Related Fault Codes
Frequently Asked Questions
What does OBD2 code P2122 mean?
OBD2 code P2122 refers to Throttle/Pedal Position Sensor/Switch D Circuit Low Input. When a vehicle powertrain module registers the fault code P2122, it points directly to an internal system malfunction identified as "Throttle/Pedal Position Sensor/Switch D Circuit Low Input". Operating your engine under this condition may degrade long-term fuel maps.
What are the most common symptoms of DTC P2122?
Drivers experiencing code P2122 typically report: Lack of engine response when pressing the gas pedal.
Is it safe to drive with trouble code P2122 active?
With P2122 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to short to ground in pedal sensor wiring.
How much does it cost to fix code P2122?
The estimated repair cost for P2122 ranges from $100 to $400 USD. Pedal assembly: $150 - $350
Pedal assembly: $150 - $350
Need Professional Diagnostic Assistance?
Always verify sensor signals and wiring integrity with an OBD2 scanner before purchasing replacement parts.
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