C0642 code meaning
Brake Pressure Sensor K Circuit High
What C0642 means
C0642 means the output of sensor K exceeds its upper limit. Electro-hydraulic brakes like Mercedes' Sensotronic Brake Control work with a high-pressure accumulator and a pedal value sensor with two Hall elements; during a pre-drive check the unit pressurises the calipers to test, among other things, its pressure sensors. A high fault on any such sensor would make the module believe the brakes are applied. Saab's 9-5 sets its sensor code above 4.75 V for 0.1 s; GM's 2019 EBCM uses 95.24 % of supply on the main channel and 94.50 % on the reference channel. No maker says which sensor would be K, so the letter cannot be linked to a location. Typical: short to 5 V or battery, lost sensor ground, internal fault.
C0642 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0642
- Brake system and ESC warning lamps on
- Brake lights or hold functions may be requested wrongly on some systems
Common causes of C0642
- PossibleSignal shorted to 5 V or battery voltage
- PossibleLost sensor ground
- PossibleInternal fault of sensor K signalled at the upper rail
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake pressure sensor kSensor wiring
What each part of C0642 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 42 | The exact fault in that area. |
What to do next
- Note C0642 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 C0642
What does C0642 mean?
C0642 means "Brake Pressure Sensor K Circuit High". C0642 means the output of sensor K exceeds its upper limit. It is a generic code, so it means the same on every make.
Is it safe to drive with C0642?
Drive gently and only to a workshop. With C0642 the car can go into limp mode (reduced power) to protect itself.
Will C0642 fail an emissions test?
C0642 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 C0642 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C0642 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.