C05B7 code meaning
Brake Booster Temperature Sensor C Circuit Intermittent/Erratic
What C05B7 means
C05B7 is meant for a temperature C signal that jumps or briefly drops out rather than failing permanently. No manufacturer documents it publicly. In Mitsubishi's Outlander PHEV the sensor C channel is judged against fixed limits with a detection time of up to one second, so short spikes there end up as C05B3 or C05B4 instead of a separate erratic code. Thermistor specialists attribute unstable readings mainly to mechanical stress: bent leads, board flex or shocks can produce intermittent contact before the part opens completely, and damaged coatings let moisture in. Because the sensor often sits on the booster's own board, a cracked solder joint is the usual suspect. The lamp may come and go with temperature or rough roads, and the fault tends to reappear after clearing.
C05B7 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of C05B7
- Brake system warning lamp flickers or appears only at times
- Code returns after clearing, often after rough roads or temperature changes
Common causes of C05B7
- Most likelyCracked solder joint or lead at the thermistor
- PossibleLoose pin or fretting corrosion at the booster connector
- Less likelyMoisture reaching the sensing element through a damaged coating
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake booster temp sensor cElectric brake booster
What each part of C05B7 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B7 | The exact fault in that area. |
What to do next
- Note C05B7 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 C05B7
What does C05B7 mean?
C05B7 means "Brake Booster Temperature Sensor C Circuit Intermittent/Erratic". C05B7 is meant for a temperature C signal that jumps or briefly drops out rather than failing permanently. It is a generic code, so it means the same on every make.
Is it safe to drive with C05B7?
C05B7 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will C05B7 fail an emissions test?
C05B7 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 C05B7 to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C05B7 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.