The engine computer runs a self-check on its own internal memory (where its programming and calibration data live) and found the data didn't pass a checksum validation — essentially, the ECU detected corruption in its own stored program data.
Symptoms
- Check engine light on, sometimes with no other symptom at all
- Occasionally erratic or inconsistent engine behavior if the corrupted data affects a specific function
- In rare cases, the engine may not start if critical calibration data is affected
Likely causes
- A voltage spike or drop (from a weak battery, bad alternator, or jump-starting incorrectly) that corrupted memory during a write operation
- A failed or interrupted software update/reflash
- Genuine internal ECU hardware failure — less common, but possible on an older module
How to diagnose it
- Check battery and charging system health first, since electrical instability is the most common trigger
- Clear the code and see if it returns — a one-time voltage glitch may not recur
- If it returns consistently, the ECU likely needs reprogramming or replacement, which is a job for a workshop with the right software
Typical fixes & cost
- Fix underlying electrical/charging issues (battery, alternator) first100–700 EUR
- ECU reprogramming/reflash at a workshop100–300 EUR
- ECU replacement, if reprogramming doesn't resolve it400–1500 EUR
Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief