Inspection readiness: why a healthy car gets turned away
No warning light, yet the station asks you to come back later. What the on-board self-tests are and how to complete them.
The car is fine, no warning light, and the inspection station says: «come back later». The reason is almost always the same — the on-board self-tests have not finished.
What readiness means
The control unit tests the catalyst, the oxygen sensors, the evaporative emission system and the rest by itself. These tests do not run all the time: they need conditions to line up — a certain temperature, speed, fuel level. Until a test completes, it counts as not ready.
The app shows these self-tests as a list: which are done and which are not.
Why they reset
- The battery was disconnected. The memory was cleared along with the results.
- The codes were cleared with a scanner. That is the same reset — which is exactly why clearing a code before an inspection is pointless: the light goes out, but the station sees unfinished tests.
- The battery was taken out for the winter or replaced.
How to drive them off
There is no universal recipe: every make has its own cycle. Usually a few trips of different kinds are enough:
- A cold start and warm-up to operating temperature, without hard acceleration.
- Twenty to thirty minutes on the motorway at a steady speed.
- A city trip with stops.
- A night standing still, so the engine cools down completely.
The evaporative system test usually will not run if the tank is below a quarter or above three quarters full — that condition is written into the control unit itself.
How to know you are ready
Open the Diagnostics tab and look at readiness. When every test the car supports is marked as complete, you can go to the station.
One unfinished test on a petrol car is tolerated in most countries, two or more means refusal. The rule depends on the country, so check it in advance.
Codes that may show up along the way are explained in the reference.
Why a scanner shows dozens of codes on a healthy car
Incomplete monitors are also the reason for a strange number in apps and at workshops: ask a unit «how many codes have any status bit at all» and it honestly answers in the dozens. On a live Geely Coolray the engine answers 94 and the gearbox 70 — with zero active faults. We took it apart step by step in Geely over OBD-II: what matters is active faults and readiness, not the total count.
