C05CE code meaning
Brake Master Cylinder Piston Position Sensor B Circuit Voltage Low
Chassis system Generic code C05xx codes Check engine light
What C05CE means
Here the second, PWM-coded output (channel B) of the piston travel sensor stays permanently low. GM's XT4 brake module and the later 23OBDG07 and 25OBDG03B tables interpret a constant low level for 0.2 s as the signal line shorted to ground, Type A, one trip, MIL. Because a PWM line at 0 V also results when the sensor loses its supply or ground, a dead channel B together with a working channel A suggests a wiring fault close to the second output, while both channels failing hints at the shared supply (C05D1). The module can usually still brake with channel A, but with less redundancy. Inspect the harness at the booster for crush or water damage before condemning the unit. C05CD is the stuck-high case.
C05CE at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C05CE
- Malfunction indicator lamp, brake system warning
- Possibly reduced assist or regeneration off
Common causes of C05CE
- Most likelyPWM signal line shorted to ground
- PossibleSensor channel B without supply or ground
- PossibleOutput stage of channel B failed low
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Master cylinder pos sensor bSensor wiring
What each part of C05CE means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| CE | The exact fault in that area. |
What to do next
- Note C05CE and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C05CE
What does C05CE mean?
C05CE means "Brake Master Cylinder Piston Position Sensor B Circuit Voltage Low". Here the second, PWM-coded output (channel B) of the piston travel sensor stays permanently low. It is a generic code, so it means the same on every make.
Is it safe to drive with C05CE?
Drive gently and only to a workshop. With C05CE the car can go into limp mode (reduced power) to protect itself.
Will C05CE fail an emissions test?
C05CE is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C05CE to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C05CE clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.