Worn or corroded accelerator pedal position sensor connector terminals; Chafed or broken wire in the APP sensor 3 signal circuit; Failed accelerator pedal position sensor assembly (internal potentiometer fault); Poor ground connection for the APP sensor at the pedal or chassis; Water intrusion into the pedal sensor connector or harness; ECM internal fault on the APP sensor 3 input circuit (rare)

DTC codes / GM codes / P1287

P1287 · GMAccelerator Pedal Position Sensor 3 Circuit Low Voltage

Q: What does code P1287 mean?

Accelerator Pedal Position Sensor 3 Circuit Low Voltage. P1287 on a GM vehicle means the engine control module (ECM) has detected an abnormally low voltage signal from the third circuit of the accelerator pedal position (APP) sensor, which is a redundant sensor used to verify driver demand. The ECM compares this signal against the other APP sensor circuits and sets the code when the voltage falls below the expected threshold, often triggering reduced engine power mode.

P1287 on a GM vehicle means the engine control module (ECM) has detected an abnormally low voltage signal from the third circuit of the accelerator pedal position (APP) sensor, which is a redundant sensor used to verify driver demand. The ECM compares this signal against the other APP sensor circuits and sets the code when the voltage falls below the expected threshold, often triggering reduced engine power mode.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Reduced engine power message or limp mode with limited throttle response
Illuminated check engine light and possibly a flashing throttle warning lamp
Hesitation or stumble when pressing the accelerator pedal
Inconsistent or surging engine speed despite steady pedal input
Often no symptoms besides the warning light if the fault is intermittent

Common causes, most likely first

Worn or corroded accelerator pedal position sensor connector terminals
Chafed or broken wire in the APP sensor 3 signal circuit
Failed accelerator pedal position sensor assembly (internal potentiometer fault)
Poor ground connection for the APP sensor at the pedal or chassis
Water intrusion into the pedal sensor connector or harness
ECM internal fault on the APP sensor 3 input circuit (rare)

How to diagnose and fix it

Inspect the APP sensor connector and harness for corrosion, water intrusion, or loose pins
Check the APP sensor 3 signal voltage with a scan tool while slowly pressing the pedal to confirm the low reading
Measure resistance and continuity of the APP sensor 3 circuit from the pedal connector to the ECM
Verify the sensor ground circuit has less than 0.1 volts drop under load
Replace the accelerator pedal position sensor assembly if the signal circuit and grounds test good
Clear the code and perform a throttle relearn or idle relearn procedure if required
Road test the vehicle through several ignition cycles to confirm the code does not return

Why APP Sensor 3 Codes Mislead

A low voltage on APP sensor 3 can be caused by a poor ground shared with other sensors, so always check ground integrity before condemning the pedal assembly.
Intermittent P1287 often appears only when the pedal is at a specific position, so a live data recording during a test drive is more reliable than a static voltage check.
The APP sensor is a dual or triple redundant design, and a fault in one circuit may not disable the vehicle but will still set the code and reduce throttle authority.
Aftermarket floor mats or pedal covers that restrict pedal travel can cause the ECM to see implausible APP voltages and set this code.
A weak battery or charging system fault can cause low reference voltage to the APP sensor, mimicking a sensor failure and leading to unnecessary parts replacement.

Can I keep driving with P1287?

You can usually drive the vehicle to a repair shop, but expect reduced engine power and avoid heavy acceleration or highway merging until the fault is repaired. If the vehicle enters limp mode or the throttle becomes unresponsive, pull over safely and arrange a tow.

Tools that help

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