C05A3 code meaning
Wheel Speed Sensors Supply Circuit High
Chassis system Generic code C05xx codes Check engine light
What C05A3 means
Active wheel speed sensors are fed by the ABS module and send their pulses back as a current on the same pair of wires, as HELLA explains. C05A3 reports that this common supply is too high or cannot be switched off. GM's 2016 and 2019 hybrid brake controllers look for reverse current on the supply line, the sign of a short to the battery feed, for over 3.5 s. A 2019 GM EBCM with a system ASIC uses C05A3 for two cases: the sensor supply exceeds its overvoltage limit, after which the ASIC turns off all four high-side switches, and a periodic test in which a supposedly switched-off high side is still live. Both are Type A with MIL. Allegro rates its wheel speed sensor IC for 24 V and clamps at 28 V. With no wheel speeds, ABS, ESC and traction control stop working.
C05A3 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C05A3
- ABS, traction and stability control warning lamps on at the same time
- Several or all wheel speed signals lost, speedometer may drop out
- MIL on (GM)
Common causes of C05A3
- Most likelyWheel speed sensor wire chafed and shorted to battery voltage
- PossibleSupply switch or ASIC in the brake module stuck on
- Less likelyWater in a wheel speed sensor connector bridging to a powered circuit
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Wss supplyWheel speed sensorABS control module
What each part of C05A3 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A3 | The exact fault in that area. |
What to do next
- Note C05A3 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 C05A3
What does C05A3 mean?
C05A3 means "Wheel Speed Sensors Supply Circuit High". Active wheel speed sensors are fed by the ABS module and send their pulses back as a current on the same pair of wires, as HELLA explains. It is a generic code, so it means the same on every make.
Is it safe to drive with C05A3?
Drive gently and only to a workshop. With C05A3 the car can go into limp mode (reduced power) to protect itself.
Will C05A3 fail an emissions test?
C05A3 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 C05A3 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will C05A3 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.