Faulty brake pedal position sensor B, or one that is worn or out of range; Damaged wiring, chafing or corrosion in the sensor signal, reference or earth circuit; Poor connection at the sensor or control unit connector, such as loose or corroded pins; Sensor or pedal bracket misaligned, loose or wrongly fitted after earlier work; Low or unstable supply voltage from a weak battery or charging fault; Brake light switch or related circuit fault that causes a disagreement between signals; Internal fault in the control unit or an outdated calibration on a specific model.

P05DC

Brake Pedal Position Sensor B Circuit Range/Performance.

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
DC: FaultThe specific fault in that area

What it means

P05DC means the engine or powertrain control unit has found that the signal from brake pedal position sensor B is outside the expected range or does not agree with what it should be. The control unit usually compares it with another brake pedal sensor or switch, or with the brake light switch and brake pressure signals. If the readings disagree or do not follow pedal movement, it sets the code. How the sensor is used and which circuit is 'B' depends on the model.

Symptoms

Warning light on, such as the engine light or a brake system warning
Brake lights stuck on, or not working when the pedal is pressed
Cruise control or adaptive cruise not working
Reduced engine power or limp mode on some models
Stop/start system disabled
Erratic idle or delayed throttle response on some models

Possible causes

Faulty brake pedal position sensor B, or one that is worn or out of rangelikely
Damaged wiring, chafing or corrosion in the sensor signal, reference or earth circuitlikely
Poor connection at the sensor or control unit connector, such as loose or corroded pinslikely
Sensor or pedal bracket misaligned, loose or wrongly fitted after earlier workpossible
Low or unstable supply voltage from a weak battery or charging faultpossible
Brake light switch or related circuit fault that causes a disagreement between signalspossible
Internal fault in the control unit or an outdated calibration on a specific modelrare

How to diagnose

Read all stored codes and freeze frame data, and note whether other brake, cruise or pedal sensor codes are present
Check that the brake lights work correctly and switch off fully when the pedal is released
Inspect the pedal assembly, sensor mounting and linkage for damage, looseness or misalignment
Inspect the sensor wiring and connector for chafing, water ingress, bent pins and corrosion
Watch live data for brake pedal position sensor A and B while pressing and releasing the pedal slowly, and look for jumps, dropouts or mismatches
Check the sensor supply, signal and earth circuits against the manufacturer's data, and test for shorts or high resistance
Test battery condition and charging voltage, as low voltage can upset sensor readings
Check for software updates or technical bulletins for the specific model and engine

How to fix

Repair or replace damaged wiring and clean or replace faulty connector terminals
Replace the brake pedal position sensor if its signal is out of range or erratic
Refit or adjust the sensor and pedal assembly to the correct position, and carry out any learn or calibration procedure the manufacturer specifies
Replace or repair the brake light switch if it is faulty
Fix battery or charging faults, then clear the code and road test to confirm it does not return
Apply an updated control unit calibration only if the manufacturer lists it as a fix for this fault

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, but fix it soon. Check that the brake lights work properly before driving, as faulty brake lights are unsafe and illegal, and stop driving if the brakes feel abnormal or power is limited.

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