Faulty accelerator pedal position sensor (integrated in the pedal module).; Worn or corroded electrical connector at the pedal sensor or throttle body.; Damaged wiring harness between the pedal sensor and the ECM.; Contamination or mechanical binding in the accelerator pedal assembly.; Failed throttle body or dirty throttle plate causing correlation errors.; Software glitch in the ECM requiring reprogramming.; Poor ground connection for the pedal sensor circuit.

DTC codes / BMW codes / P1120

P1120 · BMWPedal Position Sensor Circuit

Q: What does code P1120 mean?

Pedal Position Sensor Circuit. P1120 on BMW vehicles indicates that the engine control module (ECM) has detected an implausible or missing signal from the pedal position sensor circuit, which typically involves the accelerator pedal module and its two redundant sensors. The ECM compares these signals to each other and to expected values; when they disagree or fall out of range, it sets this code and may restrict engine power.

P1120 on BMW vehicles indicates that the engine control module (ECM) has detected an implausible or missing signal from the pedal position sensor circuit, which typically involves the accelerator pedal module and its two redundant sensors. The ECM compares these signals to each other and to expected values; when they disagree or fall out of range, it sets this code and may restrict engine power.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illuminated check engine light, often accompanied by the electronic throttle control (ETC) warning light.
Reduced engine power or limp mode, where the vehicle may not rev beyond idle or a low threshold.
Poor or delayed throttle response when pressing the accelerator pedal.
Unexpected engine speed fluctuations or surging while driving.
Often no symptoms besides the warning light, especially if the fault is intermittent.

Common causes, most likely first

Faulty accelerator pedal position sensor (integrated in the pedal module).
Worn or corroded electrical connector at the pedal sensor or throttle body.
Damaged wiring harness between the pedal sensor and the ECM.
Contamination or mechanical binding in the accelerator pedal assembly.
Failed throttle body or dirty throttle plate causing correlation errors.
Software glitch in the ECM requiring reprogramming.
Poor ground connection for the pedal sensor circuit.

How to diagnose and fix it

Read fault memory with a BMW-capable scan tool and record freeze-frame data to understand when the code set.
Visually inspect the accelerator pedal module, connector, and wiring for damage, corrosion, or loose pins.
Check live data for both pedal position sensor signals and compare their voltages for plausibility.
Perform a resistance and continuity test on the sensor circuit wiring between the pedal and ECM.
Clean the throttle body and perform a throttle adaptation reset if contamination is found.
Replace the accelerator pedal module if sensor signals are erratic or out of specification.
After repair, clear fault memory and verify the code does not return during a test drive.

Pedal Sensor Diagnostics Beyond the Pedal

A common misdiagnosis is replacing the accelerator pedal when the real fault is a chafed wire in the harness near the pedal assembly or a corroded connector pin.
The throttle body and pedal sensor signals are cross-checked by the ECM; a dirty or failing throttle body can set P1120 even when the pedal sensor itself is fine.
Intermittent P1120 codes often appear after battery replacement or voltage drops, so always check battery health and ground connections before condemning parts.
On some BMW models, the pedal sensor is part of a matched pair with the throttle body, and replacing only one may require a software adaptation or coding.
The code can be stored without illuminating the check engine light if the fault is brief, so a full scan of all modules is essential for accurate diagnosis.

Can I keep driving with P1120?

If the vehicle is in limp mode or the throttle response is severely reduced, avoid driving at high speeds or in heavy traffic and seek repair promptly. If only the warning light is on and the car drives normally, you can drive cautiously to a workshop, but monitor for any change in performance.

Tools that help

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