Why is my forward collision warning light on?
Reviewed by the Skyview Auto Glass technical team — NWRD-, ASE- and DINITROL-trained technicians · Updated November 2026
Quick answer
A forward collision warning light usually means the system is off, blocked, or seeing a fault. Common causes are a dirty or obstructed windshield in front of the camera, heavy rain or snow, a fault code, or a camera that was not recalibrated after glass work. Clean the glass first; if it stays on, have the system scanned.
What the warning tells you
- The light is on with a "system unavailable" message
- The camera cannot see the road clearly, often from dirt, rain, snow, or glare on the glass in front of the lens.
- The light came on after a windshield replacement
- The forward camera was not recalibrated, or the calibration did not finish. The system flags its own unverified aim.
- A "pre-collision system malfunction" message
- A fault code is stored. The system needs a scan to find whether the cause is the camera, a sensor, or the wiring.
What to check first
- Clean the outside of the windshield in front of the camera, behind the rearview mirror.
- Check for stickers, toll tags, or a dash cam blocking the camera’s view.
- Look for condensation or fogging inside the camera housing.
- See if the message clears after the weather improves or the glass dries.
- Note whether the light appeared right after a windshield or front-end repair.
After a windshield replacement, it is usually calibration
If the warning appeared after the glass was replaced, the forward camera behind it was removed and refitted, and its aim shifted. Skyview recalibrates the camera as part of the replacement — static calibration takes 30 to 60 minutes, dynamic adds a 15 to 30 minute drive, and some vehicles need both. It typically runs $95 to $300 with a pre-scan and post-scan, and if the warning stays on after Skyview calibrates, Skyview comes back and redoes it.
When to have the system scanned
A forward collision warning light that stays on after the glass is clean and the weather is clear points to a fault code or a calibration gap. The system stores a code that says whether the camera, a radar sensor, or the wiring is at fault, and a scan reads it. A dirty lens or bad weather clears on its own; a stored code does not.
If the light appeared after a windshield replacement and the camera was not recalibrated, that is the first thing to fix. See our guide on signs your windshield camera needs recalibration and our ADAS calibration service.
More questions about the forward collision warning light
Why is my forward collision warning light on?
The system is off, blocked, or seeing a fault. Clean the glass in front of the camera, wait for bad weather to clear, and if it stays on, have the system scanned for a fault code.
What does forward collision warning unavailable mean?
The camera cannot see the road well enough to work, usually from dirt, rain, snow, or glare on the windshield. Clean the glass and see if it clears; if not, have it scanned.
Why is my pre-collision system malfunctioning after a windshield replacement?
The forward camera behind the glass was not recalibrated, so its aim is unverified. The camera needs to be re-aimed as part of the replacement.
Related guides
More in ADAS cameras and calibration
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