fault code guide
C0035: Left Front Wheel Speed Sensor Circuit Malfunction
This code means the anti-lock braking computer has lost a reliable signal from the sensor on the front left wheel. Your ordinary brakes still stop the car, but emergency anti-lock braking and stability control are turned off.
How it shows up: You will usually see an amber ABS light alongside the traction or stability control warning light on your instrument cluster. The car will drive and stop normally under gentle pressure, but the fault code C0035 will show up on an OBD scanner.
Updated 9 November 2026
Can I keep driving?
Service soon
You can drive home or to a garage, but your wheels may lock up during sudden hard braking in wet or icy conditions because the safety assist systems are disabled.
What to do right now
- 1Gently test your brakes in a safe, quiet spot to confirm the pedal feels firm and responsive.
- 2Check that the red brake warning light is not illuminated, as only the amber ABS light should be active with this fault.
- 3Drive cautiously at moderate speeds and leave extra stopping distance, especially on wet or slippery roads.
- 4Book the car into a garage promptly to have the sensor and wiring inspected.
Likely causes
Most likely first.
- Likely
Damaged sensor wiring or corroded plug
The wiring runs down the suspension arm where it flexes constantly and is exposed to road spray, grit and winter salt, which causes broken copper strands or corroded pins.
- Likely
Failed wheel speed sensor
The internal pickup coil or electronic circuit inside the sensor degrades over time from heat, moisture ingress and road vibrations until it fails completely.
- Possible
Contaminated or cracked reluctor ring
The magnetic ring or toothed tone ring that the sensor reads can gather metallic brake dust or rust, breaking the clean magnetic signal the computer expects.
- Possible
Worn front wheel hub bearing
Excessive mechanical play in a failing wheel bearing can cause the reluctor ring to wobble away from the sensor tip, interrupting the circuit signal.
What you can check yourself
Park somewhere safe and level, engine off, before you start.
- 1
Check the dashboard warning colours
Switch on the ignition and check the instrument cluster. If the red brake warning light stays lit, stop driving immediately; if only the amber ABS and traction control lights are on, normal braking remains operational.
- 2
Check the brake pedal feel
While parked safely with the engine running, press the brake pedal firmly. It should feel hard and stay in place without slowly sinking to the floor, confirming hydraulic pressure is intact.
- 3
Inspect the wiring behind the front left wheel
Turn the steering wheel fully to the right, apply the handbrake and switch off the engine. Look behind the front left tyre with a torch to check the thin wire leading to the brake hub for obvious splits, chafing or disconnected plugs.
- 4
Inspect the wheel arch for heavy debris
Look for built-up mud, road grime or loose road debris caught around the hub assembly that may have fouled the sensor connector or severed the loom.
Rough cost to fix
Rough estimateTypical prices in Ireland (€) and the UK (£), from an independent garage up to a main dealer. The total repair cost depends mainly on whether the fault is in a basic detachable sensor or a magnetic ring sealed inside the wheel bearing itself.
Left front wheel speed sensor replacement
- Do it yourself
- €30–80£25–70 in the UK
- At a garage
- €120–220£100–190 in the UK
Wiring harness repair or plug replacement
- Do it yourself
- €15–40£10–35 in the UK
- At a garage
- €90–180£80–160 in the UK
Front wheel hub bearing replacement
- Do it yourself
- Garage job
- At a garage
- €220–420£190–360 in the UK
When to go to a garage
- Go to a garage immediately if the red brake warning light appears alongside the amber ABS light.
- Call for help if the brake pedal feels spongy, sinks under foot or requires pumping to stop.
- Book an appointment if replacing the sensor does not clear the fault, which points to a damaged hub bearing or deeper wiring break.
- Have the repair carried out before your upcoming NCT or MOT test, as an illuminated ABS light is a fail on both tests.
Questions drivers ask
Can I drive with fault code C0035?
Yes, you can safely make short journeys or drive straight to a garage because standard hydraulic brakes continue to work. However, you will not have anti-lock braking or stability control in an emergency, which increases your stopping distance and skid risk in the wet. Drive gently and leave plenty of room between you and the car in front.
Will clearing fault code C0035 fix the problem?
No, clearing the fault code with an OBD scanner only wipes the computer memory temporarily. As soon as you switch on the ignition or move the car, the ABS control module runs an electrical check. If the broken wire or faulty sensor is still present, the warning lights will trigger again almost immediately.
Will my car fail its NCT or MOT with code C0035?
Yes, an illuminated ABS or stability control warning light is an automatic fail on both the Irish NCT and the UK MOT. Testers look for the ABS symbol to light up during the ignition sequence and turn off once the engine runs. The underlying fault must be repaired and the dashboard warning extinguished to pass the test.
What is the difference between C0035 and C0040?
Code C0035 indicates an electrical fault on the front left wheel speed circuit, whereas C0040 points to the front right wheel speed circuit. Both trigger the same dashboard lights and symptoms, but the exact code tells the mechanic precisely which side of the car requires inspection.
Test rules here are for the National Car Test in Ireland (NCT) and the MOT in the UK. Elsewhere, check the regulations of your own country or state before going for a vehicle test.
Warning lights you may see
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General guidance for most cars, not a diagnosis of yours. Details differ by make, model and year - check your handbook, and if in doubt, don't drive.