What does a pending, stored or permanent code mean?

How does a fault go from pending to confirmed?

For many emissions faults, the control unit waits to see the failure on two drive cycles in a row before confirming it and turning on the light. If the test passes on the second cycle, the pending code can disappear by itself.

There are exceptions: a severe misfire that can damage the catalytic converter makes the light flash right away.

What is a permanent code?

It is an OBD-II requirement in the United States that also shows up on many cars sold in Europe. The code stays stored even if you clear the faults, and an inspection can see it.

It goes away when the car runs the failed test again and passes, which can take one or several specific drive cycles.

What about history or intermittent codes?

Many manufacturers also keep a history: faults that are no longer active but happened, sometimes with a counter and the mileage. It is very useful for intermittent problems.

In modern diagnostics (UDS) each code carries a status byte saying whether it is failing now, pending, confirmed, has requested the warning light and whether the test has run since the last clear.

When does the light go off by itself?

Under the usual OBD rules, the light goes off if the test passes on three cycles in a row, and the code is eventually erased from memory after many cycles without repeating. Each manufacturer can adjust these criteria.

General guidance only: every manufacturer and model has its own details. Always follow your vehicle's manual and, if in doubt, ask a workshop.