How do you find an intermittent fault that shows no codes?
The fault comes and goes and the code reader shows nothing
The short answer
A fault code reader only shows what the car has logged. Many faults, such as a misfire under load, a wiring break that opens when warm, or a sensor drifting out of range, log nothing or the wrong thing. Finding them means reproducing the conditions while watching live data, and testing the wiring rather than swapping parts.
How we approach it
- Listen to when it happens: speed, load, temperature, weather, bumps
- Read live data and freeze-frame records, not just stored codes
- Test circuits with break-out boxes and meters, not guesswork
- Use the rolling road to recreate road conditions safely in the workshop
Help us find it faster
A short note of every time it happens saves diagnostic time and money. A phone video of the dashboard or the noise helps too.
What to do now
- Note when it happens and what you were doing.
- Tell us what has already been checked or replaced.
- Book a diagnostic assessment; we agree any further time with you first.
Draft Technical wording to be reviewed by PK before publishing.