Codes and warning lights
Can I pass an emissions inspection with a pending code?
A pending code is a fault that the ECU has seen once but not yet confirmed, so it usually does not turn on the check engine light. What counts at the inspection depends on each country's or state's procedure, but a pending code warns of a problem that may be confirmed right before the test: find out what it is and fix it before you go.
Reviewed by Daniel Morales, founder of Reprorace SL, on
What does an emissions inspection look at in the car's diagnostics?
On cars with OBD, the inspection may check the check engine light, plug a scan tool into the port and look at the codes and the readiness monitors, besides measuring emissions. What exactly is checked and what counts as a failure is set by each procedure.
A lit check engine light is a failure in many procedures; a pending code without the light usually matters less, but there is no single rule that guarantees it.
Why is clearing the code before the test not enough?
Clearing codes resets the readiness monitors to not complete, and a car with incomplete monitors may be rejected by the emissions test. And if the fault is still there, the code comes back.
The sensible thing is to read the code, fix the cause and drive for a few days so that the monitors complete before the appointment.
What if a pending code shows up a few days before?
Read it and see which system it belongs to: a small evaporative leak or a loose gas cap is not as serious as a misfire. If it is something simple, fix it and check that it does not come back.
If there is no time, ask the test center or your shop. Better to reschedule than to go with a fault that could be confirmed on the way.
General guidance only: every manufacturer and model has its own details. Always follow your vehicle's manual and, if in doubt, ask a workshop.
See what your car is saying
With the ECO-LITE you see pending and confirmed codes and the state of the monitors in your account before the inspection, and your shop can review them remotely with your permission.
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Frequently asked questions
Does a pending code turn on the check engine light?
Usually not; if the fault happens again in another drive cycle, it becomes confirmed and may turn the light on.
Can the inspection see cleared codes?
It sees that the monitors are not complete, which gives away a recent clearing or a disconnected battery.
How long does a pending code take to go away?
If the fault does not repeat, it clears itself after several drive cycles without the fault; the number depends on the manufacturer.