A diagnostic trouble code is evidence, not the whole diagnosis. DTC management should never mean deleting every code or hiding an unresolved mechanical, electrical or emissions fault.
Start with the root cause
Provide the complete code, status, frequency, freeze-frame data and the condition that triggers it. Include repairs already completed and relevant live data. A code that appears after a hardware or software change needs that history; a code caused by wiring, sensor, pressure or mechanical failure requires repair.
Use the complete alphanumeric code and identify the control unit reporting it.
RPM, load, temperature, gear, time and frequency make the symptom reproducible.
Submit the correct software with ECU, HW/SW and read method.
Explain the repair or supported software requirement and intended use.
What the workshop must provide
- Full vehicle or machine and ECU identification.
- Untouched original and current installed-file status.
- Complete diagnostic scan, not a cropped code description.
- Freeze-frame, logs and symptoms under repeatable conditions.
- Mechanical and wiring checks already performed.
- Hardware, replacement parts and coding history.
Responsible boundaries
Safety, emissions, immobiliser, communication and protection faults may have legal or operational consequences. BLAG assesses only supported, permitted requests and may require more diagnosis or decline the job. Removing the warning while leaving the fault is not a repair.
Use the diagnostic checklist and keep post-delivery evidence in the same support thread.
What a technically complete outcome looks like
The relevant fault path should be understood before any supported software scope is considered. Keep a pre-work scan, repair record and post-work scan. Confirm that unrelated diagnostics, communication faults, protection strategies and safety warnings remain available. If the same symptom returns, send the exact installed file and repeatable evidence through the original job. A dashboard without a warning lamp is not proof of repair; the workshop must verify the underlying system, live data and permitted operating condition.
Prepare and validate the job
Submit the exact original file
Open one portal job with ECU identification, HW/SW, read method, hardware, diagnostic context and the required result.