Shop Resource
Why OEMs Require Pre- and Post-Repair Scans
A pre-repair scan reads every module before teardown so the repair plan is complete; a post-repair scan, after reassembly and calibration, proves the vehicle leaves with no active faults. Most manufacturers require both, and the documentation is what insurers, attorneys, and OEMs expect.
What a pre-scan finds
Modern vehicles carry dozens of networked computers, each storing diagnostic trouble codes. Many faults never light a dashboard warning. A pre-repair scan surfaces them before teardown, so hidden damage is part of the repair plan and there are no late surprises or supplements.
What a post-scan proves
A post-repair scan, run after reassembly and any calibrations, confirms every code is resolved and the repair introduced no new faults. It is the evidence that the vehicle was returned to the manufacturer's standard.
The OEM position statements
Toyota directs a pre- and post-repair Health Check scan on every collision-damaged vehicle, noting that a scan tool is the only way to find and document many codes. FCA (Mopar) requires a wiTECH scan before and after every collision repair across all safety and security systems — and after events like a battery disconnect. Volvo requires a pre-repair scan before work begins and a post-repair scan to confirm every safety and autonomous system functions.
The documentation insurers and legal require
Documented pre- and post-repair scans justify the line items on an estimate and prove the repair met OEM standards. If a driver-assistance system fails later, that record is the shop's evidence that the vehicle was returned correctly. A proper report shows the codes found, the procedures run to OEM spec, and confirmation the systems verified clean.
Sources
- Toyota — CRIB #191, "Scanning for Electrical System Faults" (Rev. Jul 2021)
- MOPAR — 31-002-19, "Scan Tool Support Before and After Collision Repair" (Sep 2019)
- Volvo — Volvo Car USA Statement, "Pre/Post Scanning Position Statement" (Feb 2021)
Frequently asked
Quick answers
- Do OEMs actually require scanning, or is it optional?
- Most major OEMs require it in writing. Toyota, FCA/Mopar, and Volvo all publish position statements requiring pre- and post-repair scanning on collision-damaged vehicles.
- Source: Toyota — CRIB #191, "Scanning for Electrical System Faults" (Rev. Jul 2021)
- Source: MOPAR — 31-002-19, "Scan Tool Support Before and After Collision Repair" (Sep 2019)
- Source: Volvo — Volvo Car USA Statement, "Pre/Post Scanning Position Statement" (Feb 2021)
- Why scan if no warning light is on?
- Many fault codes never illuminate a dashboard light. A scan tool is the only way to find and document them — which is why the dash alone is never proof a vehicle is repaired.
- Source: Toyota — CRIB #191, "Scanning for Electrical System Faults" (Rev. Jul 2021)