Faulty brake pedal position sensor B (internal fault giving a high signal); Signal wire shorted to a voltage supply or reference wire; Open circuit in the sensor ground wire, causing the signal to read high; Corroded, loose or damaged connector terminals at the sensor or control unit; Sensor incorrectly mounted, out of adjustment or damaged by a pedal assembly fault; Fault in the control unit's internal sensor supply or input circuit.

P05DE

Brake Pedal Position Sensor B Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
DE: FaultThe specific fault in that area

What it means

P05DE means the engine or powertrain control unit has seen the signal from brake pedal position sensor 'B' sitting higher than its expected voltage range. This is a circuit fault, so it points to a short to voltage, an open ground or a faulty sensor rather than a driver action. Sensor 'B' is usually the second or redundant sensor, but its location and design vary by model and engine.

Symptoms

Engine management or other warning light on
Brake lights staying on, or not working at all
Cruise control or adaptive cruise unavailable
Reduced engine power or limp mode on some models
Stop-start system disabled
Difficulty moving the gear selector out of park on some automatic models

Possible causes

Faulty brake pedal position sensor B (internal fault giving a high signal)likely
Signal wire shorted to a voltage supply or reference wirelikely
Open circuit in the sensor ground wire, causing the signal to read highlikely
Corroded, loose or damaged connector terminals at the sensor or control unitpossible
Sensor incorrectly mounted, out of adjustment or damaged by a pedal assembly faultpossible
Fault in the control unit's internal sensor supply or input circuitrare

How to diagnose

Read all stored and pending codes and note any other brake pedal sensor, brake light switch or reference voltage codes.
Review the freeze frame data to see the conditions when the code set, such as pedal state and speed.
Check that the brake lights work correctly and are not stuck on, and inspect the pedal assembly for damage or obstructions.
Inspect the sensor wiring and connector for chafing, water ingress, corrosion, bent pins and poor terminal tension.
With a scan tool, watch the live brake pedal sensor A and B values as the pedal is pressed and released, and compare them against each other and the manufacturer's specification.
With the connector unplugged, measure the reference voltage and ground at the sensor, using the model's wiring diagram.
Check the signal wire for a short to voltage or to the reference wire, and test for continuity back to the control unit.
Check the sensor mounting and adjustment against the manufacturer's procedure, as this varies by model.

How to fix

Repair or replace damaged wiring that is shorted to voltage or open on the ground or signal wire.
Clean or replace corroded or damaged connector terminals and the connector housing.
Replace the brake pedal position sensor if its output stays high or does not match the other sensor.
Refit and adjust the sensor or pedal assembly to the manufacturer's procedure, then complete any required sensor relearn.
Replace the control unit only if all wiring and the sensor are confirmed good and the fault is traced to the unit.

Can I keep driving?

Medium severity

The car can usually be driven short-term, but faulty brake light signals and disabled driver aids make it less safe, so get it fixed soon. If the brake lights are not working or the car goes into limp mode, avoid driving until it is repaired.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.