Does clearing a fault code fix the fault? When to clear, and when not to

What does clearing a fault code do?

It clears the stored fault codes and the fault memory on supported cars. Along with that, the following also happens:

• The information about the moment of the fault, stored alongside the codes, is cleared too. With 2dakika, clearing happens after a scan, so the codes and (where the engine computer stored them) the conditions when the fault was recorded stay in that scan's report; you can share the report with your mechanic.
• Emissions readiness monitors are reset; some normal driving is needed for them to complete. These are the engine computer's own tests of systems such as the catalytic converter, the oxygen sensors and EGR; if the car reports them, the report shows how many have completed.
• If the repair solved the problem, the code doesn't come back; if it didn't, the code and the warning light come back.

What doesn't it do?

Clearing only erases the record. The engine computer runs its tests again while you drive; if the fault persists, the code is recorded again. Some codes come back as soon as the engine starts, others only under specific conditions, for example on a cold start or at a particular speed on the road. That's why clearing without removing the cause only postpones the problem.

The same goes for the check engine light: after a clear made while the fault is still there, the light comes back. In short, clearing doesn't replace a repair; it comes after one. What clearing doesn't do:

• It doesn't fix the fault: if the problem persists, the code and the warning light come back.
• It doesn't repair a faulty part, and it doesn't change the condition of the engine or the exhaust system.
• It doesn't touch key and immobilizer modules.
• It doesn't change the mileage or the VIN.

When should you clear?

If the old record stays in memory after a repair, it's harder to tell at the next scan whether the problem has occurred again. That's why the cases where clearing makes sense have to do with repairs:

• After a repair: if the cause of the fault has been found and fixed, clearing the stored code makes it easier to see whether the problem comes back.
• Records created during a repair: modules can store codes when a connector is unplugged or a part is removed. Once the repair is finished, these records can be cleared.
• After a battery replacement: while the voltage is low, some modules can store voltage or communication codes. If the mechanic has judged that these codes came from the battery work, they can be cleared.
• After clearing: drive the car normally for a few days and scan it again. If the cleared code hasn't come back, that's a good sign; if it has, the problem persists. Because some faults are recorded again only under specific driving conditions, those few days of driving matter. After a recent clear, the report suggests the same step too.

When shouldn't you clear?

In these cases, rather than clearing, you first need to find the cause or go to a workshop:

• If the cause isn't known: the code is information that helps find the fault. When the code is cleared, the information about the moment of the fault is erased from the car too; even though it stays in the 2dakika report, the mechanic won't find this record in the car when looking at it. Share the report with your mechanic first, have the repair done, then clear.
• If the warning light is flashing, or there are symptoms such as misfiring or loss of power while driving: have the car checked at a workshop instead of clearing. A flashing light is usually a sign of something more urgent, such as a serious misfire that can damage the catalytic converter.
• For safety-system warnings such as airbag or ABS: see a workshop before clearing.
• To hide a fault from a buyer or a lessee: the clearing feature may not be used for this purpose. Every clear made with 2dakika is recorded.

Clearing fault codes with 2dakika: conditions and steps

Clearing is done with "Clear fault codes" in the report's Current faults section. The engine must be off, the ignition on and the battery at 12 V or more; clearing happens within 30 minutes of the scan. Nothing is cleared without your confirmation. Scanning is read-only; the only thing written to the car is a fault-code clear you confirm.

• Scan the car; when the report is ready, go to its Current faults section.
• Tap "Clear fault codes". The app explains what clearing does and doesn't do, and asks you to confirm.
• Once you confirm, the clear runs on a single-use authorization from our server.
• Results are shown module by module; on some cars, some modules don't allow clearing.

Every clear stays on record

Every clear is recorded for the car and shows up with its date and module count in the "Cleared with 2dakika" row of the car's later reports; if there has been more than one clear, the total is shown too. This needs the VIN to be read from the car in both scans. A clear in the last 30 days appears as a warning in the report summary.

On cars that report it, the report also shows the distance driven since the fault memory was last cleared and points out a recent clear. This counter can also be reset by disconnecting the battery or by workshop work.

The decision to clear and its consequences are yours; clearing may not be used to hide a fault from a buyer or a lessee. If you're a mechanic or run a workshop, the record helps you too: the date of the clear shows in the car's later reports, and your customer can see when the fault was cleared after the repair.