C064B code meaning
Brake Pressure Sensor M Circuit Low
What C064B means
Sensor M sits below its lower signal limit. Because modules often supply several pressure sensors together, a single low code can be the visible part of a wider fault: WABCO's trailer modulator powers all active sensors jointly, so a short on one sensor supply can pull others down too, and codes for neighbouring letters may then appear at the same time. In an ESP block, Bosch describes each sensor with four contacts, two for supply and two for the analog pressure signal, which makes a shorted or contaminated spring contact a plausible cause. GM's 2019 brake module flags its secondary circuit pressure sensor low under 4.61 % of supply for 100 ms; no maker publishes C064B itself. Check the shared supply before replacing sensor M.
C064B 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 C064B
- Warning lamp on, possibly with further pressure sensor codes
- Electronic brake functions reduced to a fallback mode
Common causes of C064B
- Most likelyShared sensor supply shorted, pulling several sensors low
- PossibleSignal line or contact of sensor M shorted to ground
- Less likelySensor element failed
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 C064B means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4B | The exact fault in that area. |
What to do next
- Note C064B 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 C064B
What does C064B mean?
C064B means "Brake Pressure Sensor M Circuit Low". Sensor M sits below its lower signal limit. It is a generic code, so it means the same on every make.
Is it safe to drive with C064B?
Drive gently and only to a workshop. With C064B the car can go into limp mode (reduced power) to protect itself.
Will C064B fail an emissions test?
C064B 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 C064B to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C064B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.