Lane Assist Fault: What's Causing It and What to Do
Lane assist warning on your dashboard, often with adaptive cruise or forward collision warnings on at the same time? The same camera that runs lane assist also feeds the other systems, so when it's off, several warnings flag together. New windscreen, bumper repair, wheel alignment, even a parking knock can all trigger it. Here's what's happening and what calibration costs.
It's the camera, not the radar
Lane assist reads road markings through the camera at the top of your windscreen. That same camera feeds forward collision warning and reads speed limit signs on most cars. When it loses its aim even slightly, lane assist goes offline, and the other systems sharing it can flag at the same moment. The fix is the camera, not the radar.
Why a camera fault flags lane assist first
Lane assist is the simplest job your forward camera does: read two painted lines, warn you when you drift, sometimes steer you back. The same camera also reads speed limit signs, watches the road ahead, and feeds Forward Collision Warning. One sensor, several jobs.
Anything that disturbs the camera's aim, a glass replacement, a parking knock, a wheel alignment that changed the car's centreline, shows up as a lane assist fault first because lane reading is the most aim-sensitive job the camera does. Other warnings often follow on the same drive.
Pick your make
Make-specific guides for the cars we see lane assist faults on most often.
- By makeRead more
Volkswagen
Golf, Polo, Transporter. Camera-based Lane Assist on every VAG car (SEAT and Škoda share the same procedure).
- By makeRead more
Honda
Civic and CR-V. Honda Sensing's LKAS shares the camera with ACC and Collision Mitigation.
- By makeRead more
Toyota
Corolla, C-HR, RAV4. Lane Tracing Assist is part of Toyota Safety Sense.
- By makeRead more
Nissan
Qashqai and Juke. Lane Departure Warning shares the camera with Forward Collision Warning.
Try these checks first
- 1
Wipe the inside of the glass behind the camera
The camera sits behind the windscreen near the rear-view mirror. Use a clean microfibre cloth on the inside of the glass directly behind it. Dirt, fingerprints, or smearing from a recent screen clean can throw the camera off. Two minutes.
- 2
Check for obstructions
Stickers, parking permits, dashcam mounts, or a sat-nav clamped near the camera all break its view. Move anything within 20 to 30 cm of the camera mount and drive again.
- 3
Cycle the ignition and drive on a marked road
Switch off, lock the car, wait 60 seconds, restart. Drive 10 minutes on a road with clear lane markings. Some lane assist warnings clear on a steady drive once the camera re-locks.
- 4
Think back through the last 4 weeks
Windscreen replaced? Bumper repaired? Wheels realigned? Battery disconnected during work? Any of those can shift the camera's calibration. If the warning appeared shortly after one of those, that's the cause.
How we fix it
If the checks above don't sort it, the camera needs recalibrating. A technician realigns it to the manufacturer's reference, clears the stored fault, and confirms lane assist and any sibling systems are reading the road again before you leave.
Most cars use static calibration: a target board set at a precise distance in front of the windscreen, OBD-linked alignment routine, post-scan to confirm. A few systems also need a dynamic drive at steady speed before the camera locks. Wheel alignment is checked before any calibration starts, because a misaligned car can fail the calibration even with a perfect camera.
It's a fixed-fee job and ends with a calibration certificate. The full procedure is in our ADAS calibration guide.
Frequently asked questions
Almost always one. Lane assist, Forward Collision Warning and adaptive cruise all read from the same forward-facing camera (and on most cars, the same forward radar). When the camera's aim is off, several warnings flag the loss of confidence at the same moment. A single calibration visit usually clears them together.
Camera calibration sits in our £199 tier, which is the windscreen camera service. That covers the diagnostic scan, the calibration itself, and a calibration certificate. If the fault also involves a front radar disturbance (after bumper work, for example), the radar tier is £349 and includes up to three ADAS systems in one visit.
Most calibrations take 60 to 120 minutes in the workshop. Some cars also need a short dynamic drive at 37 mph or above on a road with clear lane markings, which adds 20 to 30 minutes. Plan for under two hours total.
Toe angle changes after a wheel alignment shift the centreline of the car relative to where the camera is pointing. Even a small adjustment moves the camera's reference enough that lane assist starts misreading the lane lines and flags a fault.
ADAS recalibration should follow any wheel alignment on a car with lane keep assist, but not every alignment garage has the equipment. If the warning appeared straight after an alignment, the missed calibration step is the cause.
Three common reasons. The calibration was run on a generic OBD tool rather than the manufacturer's software, and the system didn't fully accept it. Or the car needed a dynamic drive after the static step and didn't get one. Or an underlying problem, a wheel alignment that's off, a damaged camera bracket, wasn't fixed before the calibration. A proper pre-scan catches the third before you pay.
The warning light on the dash will be noted at MOT and can fail the car if the system was fitted from the factory. Lane assist is factory-fitted on most cars built from 2018 onward. The fix isn't to clear the light, it's to recalibrate the camera so the system actually works.
Book your lane assist calibration
Send your registration and what's been done. We come back with the price, the nearest accredited workshop, and the soonest slot.