What are pre- and post-repair diagnostic scans?

A pre-repair diagnostic scan is carried out before relevant repair activity. Depending on the vehicle, systems, equipment and repair context, it may retrieve stored or current diagnostic trouble codes, module information, available system data and relevant electronic-system status.

This can establish useful context before work, identify existing reported information, support repair planning and help identify relevant systems. It does not mean every module or every possible fault has been identified.

A post-repair scan is carried out after relevant repair work. Depending on the vehicle, systems and procedure, it may identify information reported after repair, relevant system status, issues requiring further investigation and information useful to verification or documentation.

A post-scan is not standalone proof that every system, calibration, physical repair or mechanical condition is correct, or that no further procedure is required.

The value is not simply that two reports exist. They provide diagnostic information from two different stages of the repair.

Information recorded before the work can establish useful context. Information reported afterwards can then be interpreted in relation to the work carried out, affected systems, repair procedure and diagnostic process. A difference does not automatically mean the repair caused it, and an unchanged fault should not automatically be ignored.

A diagnostic trouble code is information reported by a vehicle electronic system. It may indicate that the system has detected a condition matching its diagnostic logic.

A code alone does not necessarily establish the root cause, required repair, component replacement, calibration requirement, responsibility or exact time of failure. It needs interpretation in the context of the vehicle and repair.

Information recorded before the repair can provide useful diagnostic context by showing that a reported condition was present at that stage.

It does not always establish exactly when the underlying condition began, its physical cause, whether it is currently active or who is responsible. The diagnostic evidence provides context rather than a standalone conclusion.

Not automatically. A fault or diagnostic change identified after repair needs interpretation.

Depending on the context, it may relate to the work carried out, a system affected by the repair, an unrelated condition, a temporary condition or another diagnostic issue. A new code does not by itself prove a workmanship fault.

No. A clean post-repair scan is useful, but it does not prove that every aspect of the vehicle or repair is correct.

A clean post-repair scan does not by itself prove physical repair quality, vehicle geometry, sensor mounting accuracy, calibration accuracy, whether calibration was required, correct glass specification or the absence of every possible vehicle fault.

It can still be valuable evidence about what the vehicle's electronic systems are reporting after the work. It simply needs to be understood within the wider repair and verification process.

Clearing a diagnostic trouble code changes the stored diagnostic information. It does not, by itself, repair the condition that caused the code.

A code remaining cleared does not automatically prove the root cause was rectified, calibration is correct or the physical repair is correct.

Depending on the vehicle and repair process, diagnostic information may be recorded while components are disconnected, systems are powered in different repair states, modules or components are removed, or vehicle systems are being worked on.

That information must be interpreted in the repair context. It should not be assumed that every disconnected component creates a fault code.

ADAS-equipped vehicles contain electronic systems that may provide relevant diagnostic information. Pre- and post-repair scanning may support system identification, reported-fault checking, repair planning, applicable calibration prerequisites and post-work verification or documentation.

Diagnostic scanning is not calibration. The calibration requirement remains procedure-led, and a clean scan does not replace calibration where calibration is required.

There is no single rule that applies identical scanning requirements to every vehicle and repair.

Diagnostic requirements depend on the vehicle, repair context, work-provider requirements where applicable, and the relevant repair or diagnostic procedure. Some repair processes may require documented pre- and post-repair diagnostics, but that should not be treated as a universal legal, insurer or manufacturer rule.

Horizon uses diagnostic scanning as part of relevant ADAS and repair-support work. This may include pre-work and post-work scanning, identifying reported faults or information, supporting ADAS calibration work, and verification or documentation within Horizon's capability.

Where applicable, scan reports may be provided or attached with relevant job documentation. This does not mean every Horizon job receives identical pre- and post-repair scans or reports.