Pending, confirmed, permanent codes: why your code will not clear
Why “clearing” is not always enough
You cleared the code, the light went off, then it came back on two days later. Or the code disappeared from the main list but is still displayed in another section. This is not a bug: the engine control unit classifies each fault according to where it stands in its checks. Clearing acts on some statuses and not on others.
The four statuses, in the order they appear
| Status | What happened | Check engine light | Can a tool clear it? | Disappears on its own when… |
|---|---|---|---|---|
| Pending | The fault was seen once, not yet confirmed | Off | Yes | the next test is good (usually one trip) |
| Confirmed | The fault was seen again (often on the 2nd trip) or is serious from the start | On | Yes | it switches to “stored” after 3 trips without the fault |
| Stored | The confirmed fault has not occurred for 3 trips: light off, code kept in memory | Off | Yes | after about 40 warm-ups without recurrence |
| Permanent | Protected copy of the confirmed code | On, or off after clearing | No | the control unit runs the test again and finds it good |
A few useful details:
- A warm-up (or warm-up cycle) means, in regulatory terms, that the coolant has risen by at least 22 °C since the engine was started and reached at least 70 °C. A series of short 2 km trips often counts as none.
- Some faults are confirmed on the very first trip, without going through “pending”: for example, misfires that risk damaging the catalytic converter (flashing light).
- The “stored” status does not always go by that name: the standard simply talks about a confirmed code with the light off. It is often the one that comes as a surprise at the roadworthiness test or when buying a used car.
The permanent code, in detail
Permanent codes were made mandatory in the United States, at California's initiative, on models from around 2010, for a simple reason: to prevent people from clearing the light just before an emissions test. Many cars sold elsewhere provide them too, but not all.
What clears it:
- The control unit runs the test again on the system concerned (sensor, catalytic converter, EGR, evaporative system…) under the conditions it requires: warm engine, steady speed, specific load, minimum duration.
- The test is good: the permanent code disappears, sometimes on the next trip, sometimes after several.
For tests that run only rarely, US regulations also require a minimum amount of driving before clearing after a scan tool has been used: the figure often quoted is 15 warm-ups and 200 miles (about 320 km). In practice, remember that a permanent code can take anywhere from a few kilometres to several days of varied driving to go away, even after a genuine repair.
What does not clear it: OBD2 clearing, another adapter, other software, a disconnected battery. That is the very principle of this code.
What DiagAuto AI displays
On the Diagnostics screen, “Read fault codes” queries the engine control unit and displays the confirmed codes (including those whose light has gone off), then the “Pending codes” and “Permanent codes” sections. Each code can be explained by the AI, which suggests leads to check. For a permanent code, the app reminds you: “Cleared automatically once the control unit has verified the repair.”
The emissions checks (the “monitors”) tell you which tests have already been run since the last clearing: a “not ready” test on the system of your permanent code means that the control unit has not run it again yet, so the code cannot go away yet.
When a car does not provide permanent codes, the app says so instead of displaying a false “no codes”.
How to make a code go away for good
- Note everything before clearing: the codes, the data at the time of the fault, the emissions checks. The app offers to save the report just before clearing.
- Repair the cause: the AI and the fault code dictionary help you understand the code; a mechanic confirms before replacing a part.
- Clear once, after confirmation, with the standard OBD2 command. DiagAuto AI does not reprogram anything.
- Drive normally, with trips of at least 20 minutes, a bit of open road or dual carriageway, and a cold start after the car has been parked overnight.
- Read again: pending codes, permanent codes, emissions checks. If a pending code reappears, the repair is not sufficient. If the system's check switches to “ready” and the permanent code has disappeared, you are done.
Common mistakes
- Clearing several times a day: each clearing resets the emissions checks and delays the test that would release the permanent code.
- Believing that a light that has gone off means repaired: it goes off after 3 trips without the fault, but the code stays stored and sometimes permanent.
- Blaming the adapter when the code comes back: it only reads what the control unit sends it.
Frequently asked questions
Can another, more powerful tool clear a permanent code?
No, this is intended by the regulations: no OBD2 tool can clear it. Only the control unit removes it, after running the test again itself and finding that the fault has gone. Disconnecting the battery does not clear it either.
I have repaired it, but the permanent code is still there. Is that normal?
Yes, for a while. The code stays until the control unit has run the corresponding test again under the right driving conditions. Depending on the system, this takes one trip or several days of varied driving.
My car shows no permanent codes, is that a good sign?
Not necessarily. Not all vehicles provide permanent codes through the OBD port, especially outside the United States and on older models. DiagAuto AI tells you when the car does not provide them.