ADAS Calibration After Bumper and Windscreen Work
A 2020 compact SUV is in for a front bumper cover replacement and a windscreen replacement. The bumper cover is an OEM part, but the radar bracket was unbolted and refitted 2 mm off its witness marks during the repair. The windscreen was replaced by a mobile glass technician, and the forward-facing camera is mounted to the screen. The vehicle had no ADAS warning lights before the repair. The workshop does not own the calibration targets for this model; the franchised dealer can perform a static calibration in three days. The customer needs the vehicle today, says it "drove fine" on the way in, and the insurer has refused calibration because no diagnostic trouble code was stored. The workshop's scan tool can read codes but cannot perform the calibration.
1. Decide whether to release the vehicle without calibration and justify your decision.
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I would not release the vehicle as correctly repaired without calibration.
Technical reasoning
- The forward camera is mounted to the windscreen. Replacing the screen changes the camera's mounting position relative to the vehicle centreline and road surface, even if the new screen is the same part number.
- The radar bracket was refitted 2 mm off its witness marks. Radar aim is sensitive to bracket position; 2 mm may be outside the OEM tolerance and can shift the detection zone.
- No diagnostic trouble code does not prove correct alignment. Many ADAS faults only appear when the system is asked to perform, and a misaimed system may give no warning until it fails to detect a vehicle or pedestrian.
Commercial and legal reasoning
- The insurer's refusal to pay does not change the workshop's duty to return a safe vehicle. Calibration is part of the repair, not an optional extra.
- I would submit a supplement with the OEM calibration requirement and the dealer quote. If the insurer still refuses, I would advise the customer in writing and offer to arrange the calibration at their cost or keep the vehicle until it is done.
- I would not describe the vehicle as "fine" or roadworthy without the calibration. I would record the advice and the customer's decision.
2. Describe the pre-scan and post-scan steps and what you would do about the 2 mm radar bracket misalignment.
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Pre-scan
- Connect a battery support unit and carry out a pre-scan before repairs. Record all DTCs, software versions and freeze-frame data.
- Check tyre pressures, fuel level, ride height and suspension condition; these affect calibration.
- Inspect the radar bracket and compare it with the OEM dimensions or witness marks. Two millimetres may exceed the OEM tolerance, so I would check the procedure rather than assume it is acceptable.
Bracket correction
- If 2 mm is outside tolerance, refit or replace the bracket and restore the correct position before calibration. Do not try to compensate with the calibration target.
- Check the radar connector, mounting studs and bumper cover for damage or non-OEM fit.
Post-scan and calibration
- Reassemble the vehicle and carry out the post-scan.
- Sublet the calibration to the franchised dealer or an approved calibration centre with the correct targets, level floor and lighting. The vehicle must be at the specified ride height, tyre pressures and fuel level.
- After calibration, carry out a post-repair scan, clear codes only if the procedure allows, and road-test the system if a dynamic calibration is required.
- Record the calibration certificate, target type, floor conditions, VIN, odometer and technician. Give the customer a copy and explain that ADAS performance depends on correct wheel alignment and tyre condition.
3. The customer insists on taking the vehicle today and says they accept the risk. How would you handle the handover and what would you record?
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I would explain the risk in specific terms: the forward camera and radar may be misaimed, so automatic emergency braking, adaptive cruise control or lane-keeping may not work as designed. A signed acceptance does not remove the workshop's responsibility to repair the vehicle properly, and it does not make the vehicle safe.
I would offer practical options:
- Keep the vehicle until the dealer calibration is completed in three days and arrange a loan car or transport.
- Release the vehicle only for the purpose of taking it directly to the calibration appointment, with written advice that ADAS functions may be unavailable and should not be relied on.
- If the customer still insists on taking it, I would record that the repair is incomplete and that I advised against use.
Records to keep:
- Pre-scan and post-scan reports.
- Photographs of the radar bracket and windscreen installation.
- The OEM calibration requirement and the dealer quote.
- The insurer's refusal and my supplement.
- A file note of the conversation, the options offered and the customer's decision.
- Handover documents stating that calibration is outstanding.
I would not issue a normal quality-control sign-off or describe the vehicle as complete.