C0649 code meaning
Brake Pressure Sensor M Circuit/Open
What C0649 means
The circuit of brake pressure sensor M, the twelfth in the series, has no continuity. Where so many pressure inputs exist, they are often not reachable from outside: WABCO notes that the two rear axle pressure sensors of its truck EBS are wired inside the axle modulator, so the cabling cannot be tested from outside and a fault means work on the modulator. Passenger-car units behave similarly; Actronics points out that the ATE MK60 carries its brake pressure sensor inside the unit, while some VW models use separate sensors near the master cylinder. External sensors, as on WABCO's trailer brake, take their supply from the modulator through a plug. No carmaker assigns C0649 or the letter M. Check plug and terminals first, then the unit.
C0649 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0649
- Brake or ABS warning lamp on
- Electronic pressure control replaced by a fallback mode
Common causes of C0649
- Most likelyLoose or corroded plug at an external sensor or at the modulator
- PossibleOpen in the internal wiring of the modulator or hydraulic unit
- Less likelyBroken wire in the sensor harness
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake pressure sensor mSensor wiring
What each part of C0649 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 49 | The exact fault in that area. |
What to do next
- Note C0649 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 C0649
What does C0649 mean?
C0649 means "Brake Pressure Sensor M Circuit/Open". The circuit of brake pressure sensor M, the twelfth in the series, has no continuity. It is a generic code, so it means the same on every make.
Is it safe to drive with C0649?
Drive gently and only to a workshop. With C0649 the car can go into limp mode (reduced power) to protect itself.
Will C0649 fail an emissions test?
C0649 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 C0649 to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will C0649 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.