Clearing OBD fault codes and the ITV: what you need to know
What happens when you clear an OBD code, why it comes back, how the Spanish ITV detects it on Euro 5 and Euro 6 cars and how to find out the repair cost.
Clearing a code does not fix the fault
With an OBD reader, or at a garage, you can clear any stored fault code and turn off the engine light. But clearing fixes nothing: if the cause is still there, the engine computer detects it again and the code comes back, sometimes on the same trip and sometimes after several drive cycles.
So the sensible thing is to read the code, write it down (with what you noticed and when it happened), repair the cause and only then clear it to check that it does not come back.
| Situation | What happens | Recommended |
|---|---|---|
| Cleared without repairing | The light goes out, but the code returns when the computer detects the fault again | Repair first, clear afterwards |
| Cleared just before the ITV | On Euro 5 or later cars, the inspection reads the OBD and can see it was cleared shortly before | Do not do it: it is a defect at the inspection |
| Repaired and cleared | If the code does not return over the next few days, the repair worked | Check over several trips |
The engine light at the Spanish ITV
- According to the ITV stations' procedure manual, as quoted by the specialist press, an engine fault light that stays on after starting is a major defect on cars registered since 1 January 2008: the result is a fail until it is repaired.
- If the inspection can see that faults were cleared very recently (within the last hour or kilometre of driving, according to the same source), that is also a major defect.
- The rules may change with new versions of the manual: if in doubt, ask your ITV station.
How much does it cost to fix a code?
- It depends on the cause: a loose connector or a sensor is not the same as the main part of the system.
- It also depends on the car and the garage: parts, labour hours and the hourly rate vary a lot.
- First the cause has to be confirmed with a diagnosis; then DATAIAO's repair cost tool gives you a range for your car.
See also
- OBD code dictionary
- Check engine light on
- Checklist to pass the ITV
- How much does it cost to repair your car?
Sources
- Diariomotor: the engine fault light and the ITV (quotes the ITV stations' procedure manual; Spanish)
- RACE: the emissions test at the ITV and the OBD readout (Spanish)
- Royal Decree 920/2017, art. 11: inspection defects and results (Spanish text on Iberley)
Reviewed in October 2026. General information: the actual cause depends on your car and is confirmed with a diagnosis. How we make our content
Guidance only. ITV rules may change: if in doubt, check with your inspection station.