Pre- and Post-Repair Scans: The Step Too Many Shops Skip
A modern car can have a dozen fault codes and no warning light. If nobody scans it, nobody knows.
A current luxury vehicle runs somewhere between fifty and a hundred networked control modules. Most of them can log a fault without illuminating anything on the dash. That means a car can come out of a collision with a disabled blind-spot monitor, a failed restraint-system self-test, or a seat-position sensor fault, and look completely normal from the driver's seat.
A pre-repair scan is run before any disassembly begins. It produces a documented list of every stored and active fault code in the vehicle. This does two things. It tells the technicians what systems the collision actually affected, which frequently reveals damage that no visual inspection would find. And it establishes a baseline, so there is no later dispute about whether a fault existed before the shop touched the car.
A post-repair scan is run after the repair is complete, and it verifies the opposite: that every code has been addressed, that every module that needed initialization got it, and that nothing new was introduced during disassembly and reassembly. Unplugging and reconnecting connectors is normal repair work, and it occasionally leaves a module unhappy in a way only a scan will surface.
Nearly every major manufacturer has issued a position statement requiring pre- and post-repair scanning on collision-damaged vehicles. These are not shop preferences; they are published OEM requirements, and they are the documentation we attach when an insurer questions the line item.
Insurers sometimes push back on scanning as an add-on, particularly on repairs that look minor. The counterargument is straightforward: a bumper impact on a car with forward radar, park sensors, and pedestrian detection is not a cosmetic event. The systems behind that bumper either work correctly afterward or they do not, and the only way to know is to ask the car.
Scanning is also not the same as calibration, and the two get conflated. A scan reads and clears fault codes. Calibration physically re-aims and re-teaches a sensor to a known reference. A camera can pass a scan with no fault codes and still be aimed several degrees off after a windshield replacement, which is exactly the failure mode that puts a lane-keeping system in the wrong lane. Both steps are required, and they are separate.
One practical note for owners: ask for both scan reports at delivery. They are printable documents with time stamps. A shop that performed them will hand them over without hesitation, and they belong in the file with the rest of your repair documentation — particularly if you may pursue a diminished value claim later.
We scan every collision vehicle in and out, without exception, and the reports go to you and to the insurer. If another shop repaired your car recently and you were never given one, that is worth following up on. Call (310) 988-2848 and we can scan it and tell you what the car has to say.