C05F1 code meaning
Rear Drive Shaft Speed Sensor Circuit High
What C05F1 means
Here the rear drive shaft speed signal reads above its valid range, as caused by a short to supply voltage, a damaged sensor IC or a fault at the module input. With a two-wire Hall sensor the module watches the current between a low and a high level (Allegro A19420: about 7 and 14 mA); a current clearly above the upper band cannot be a speed pulse. Without a plausible prop shaft speed, a disconnecting AWD system cannot judge when the rear driveline has caught up with the wheels, which the American Axle and BorgWarner patents require before engagement. Audi's quattro ultra uses such a sensor as G970. No manufacturer publishes C05F1; C05F0 is the low case, C05F4 the plausibility check.
C05F1 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C05F1
- AWD warning, all-wheel drive not connected
- Fault sets immediately at ignition on
Common causes of C05F1
- Most likelySensor signal line shorted to supply voltage
- PossibleDamaged sensor IC drawing excessive current
- Less likelyFaulty sensor input in the AWD module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Rear drive shaft speed sensor
What each part of C05F1 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| F1 | The exact fault in that area. |
What to do next
- Note C05F1 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 C05F1
What does C05F1 mean?
C05F1 means "Rear Drive Shaft Speed Sensor Circuit High". Here the rear drive shaft speed signal reads above its valid range, as caused by a short to supply voltage, a damaged sensor IC or a fault at the module input. It is a generic code, so it means the same on every make.
Is it safe to drive with C05F1?
Drive gently and only to a workshop. With C05F1 the car can go into limp mode (reduced power) to protect itself.
Will C05F1 fail an emissions test?
C05F1 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 C05F1 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C05F1 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.