Worn or corroded electrical connector at the throttle body or accelerator pedal sensor; Chafed or broken wiring in the sensor circuit due to vibration or heat; Faulty throttle position sensor or accelerator pedal position sensor; Internal intermittent fault in the sensor itself; Poor ground connection for the sensor circuit; Contamination or carbon buildup on the throttle plate or sensor contacts; ECM software glitch or internal fault (less common)

DTC codes / P21xx · Fuel and air metering / P2124

P2124Throttle/Pedal Position Sensor/Switch 'D' Circuit Intermittent

P2124 indicates that the engine control module (ECM) has detected an intermittent signal from the throttle or pedal position sensor circuit designated as 'D'. This sensor is typically the second or redundant sensor in a drive-by-wire throttle system, and the ECM sets the code when the voltage signal momentarily drops out or becomes erratic.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Intermittent hesitation or stumble during acceleration
Reduced engine power or limp mode, especially under load
Unstable idle speed or surging
Poor throttle response or delayed acceleration
In rare cases, the engine may stall or refuse to start

Common causes, most likely first

Worn or corroded electrical connector at the throttle body or accelerator pedal sensor
Chafed or broken wiring in the sensor circuit due to vibration or heat
Faulty throttle position sensor or accelerator pedal position sensor
Internal intermittent fault in the sensor itself
Poor ground connection for the sensor circuit
Contamination or carbon buildup on the throttle plate or sensor contacts
ECM software glitch or internal fault (less common)

How to diagnose and fix it

Inspect the sensor connectors for corrosion, tightness, and proper seating; clean and apply dielectric grease if needed
Perform a wiggle test on the wiring harness while monitoring live data to identify intermittent opens or shorts
Check the sensor reference voltage and ground circuits with a multimeter to ensure they are stable
Remove and clean the throttle body and sensor contacts if contamination is evident
Replace the throttle position sensor or accelerator pedal position sensor if resistance or voltage output is erratic
Repair or replace any damaged wiring or connectors in the affected circuit
Clear the code and perform a throttle relearn procedure if required by the manufacturer

Intermittent faults demand patience and live data

Intermittent codes like P2124 often leave no stored freeze-frame data, so a technician must rely on live data monitoring during a test drive to catch the glitch.
A common misdiagnosis is replacing the throttle body when the real problem is a worn connector or chafed wire that only acts up under vibration.
The 'D' circuit is usually the redundant sensor in a dual-sensor design, so a failure may not cause immediate drivability issues but can trigger limp mode as a safety precaution.
Aftermarket air intake systems or poor workmanship during previous repairs can disturb the sensor wiring, leading to intermittent faults.
Some vehicles require a throttle position sensor relearn after replacement, and skipping this step can cause the code to return even with new parts.

Can I keep driving with P2124?

If the check engine light is on but the vehicle drives normally, you can drive cautiously to a repair shop, but avoid aggressive acceleration or heavy loads. If the vehicle enters limp mode or hesitates severely, stop driving and have it towed to prevent unsafe situations.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.