Failed accelerator pedal position sensor A (worn tracks or internal fault); Corroded, chafed, or broken wiring in the pedal sensor harness or connector; Poor ground connection for the pedal position sensor circuit; Low reference voltage supply from the ECM to the sensor (shorted or high-resistance circuit); Contamination or mechanical binding at the pedal pivot or sensor linkage; ECM internal fault on the sensor input channel (least likely)

DTC codes / Jaguar codes / P1122

P1122 · JaguarPedal Position Sensor A Circuit Low Input

Q: What does code P1122 mean?

Pedal Position Sensor A Circuit Low Input. P1122 on a Jaguar means the engine control module (ECM) has detected a low voltage signal on the circuit for pedal position sensor A, which is one half of the accelerator pedal position (APP) sensor assembly. The ECM expects a specific voltage range as the pedal moves, and a sustained low reading tells it the sensor, its wiring, or its reference circuit is not behaving as designed.

P1122 on a Jaguar means the engine control module (ECM) has detected a low voltage signal on the circuit for pedal position sensor A, which is one half of the accelerator pedal position (APP) sensor assembly. The ECM expects a specific voltage range as the pedal moves, and a sustained low reading tells it the sensor, its wiring, or its reference circuit is not behaving as designed.

SystemPowertrain

Code typeJaguar specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Reduced engine power or limp-home mode with a sluggish throttle response
Inconsistent or delayed acceleration when pressing the accelerator pedal
Engine idle that hangs high or fluctuates unexpectedly
Cruise control may become inoperative or disengage on its own
In rare cases, the engine may refuse to rev above idle

Common causes, most likely first

Failed accelerator pedal position sensor A (worn tracks or internal fault)
Corroded, chafed, or broken wiring in the pedal sensor harness or connector
Poor ground connection for the pedal position sensor circuit
Low reference voltage supply from the ECM to the sensor (shorted or high-resistance circuit)
Contamination or mechanical binding at the pedal pivot or sensor linkage
ECM internal fault on the sensor input channel (least likely)

How to diagnose and fix it

Connect a scan tool and read live accelerator pedal position voltages for both sensor tracks while slowly pressing and releasing the pedal to confirm the low signal on sensor A.
Visually inspect the pedal sensor connector and harness for corrosion, water intrusion, or chafed wires, and clean or repair as needed.
Measure reference voltage and ground at the sensor connector with a multimeter, comparing against Jaguar specifications for your model.
Perform a voltage drop test on the ground and signal return circuits to rule out high resistance that mimics a failed sensor.
If wiring and voltages check out, remove and inspect the pedal assembly for mechanical wear or binding, then replace the APP sensor if internal failure is confirmed.
Clear the code and perform a pedal position relearn or throttle adaptation procedure if required for your Jaguar model, then road test to verify the repair.

What a low pedal signal really tells you

A low input code often comes from a poor ground or reference voltage drop rather than a dead sensor, so always measure voltage at the sensor connector before condemning the pedal assembly.
Jaguar APP sensors use two opposing signal tracks for redundancy, and a fault in only one track can set P1122 while the other track still reads normally, which can mislead a quick scan-tool check.
Water ingress into the pedal connector or footwell harness is a common cause on older Jaguar models, especially where the cabin filter or drain tubes have been neglected.
After replacing the pedal sensor, some Jaguars require a relearn or adaptation procedure, and skipping it can leave the code stored or cause a poor idle.
A low signal can also be set by a mechanical issue such as a worn pedal pivot that prevents the sensor from returning to its expected rest voltage.

Can I keep driving with P1122?

You can usually drive the car to a workshop, but expect reduced power or limp-home mode and avoid heavy traffic or situations that demand sudden acceleration. If the pedal response becomes erratic or the engine will not rev, stop driving and arrange a diagnostic scan.

Tools that help

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