PID 31km
Distance since codes cleared
Distance driven since the codes were cleared. Together with PID 4E (minutes) and PID 30 (warm-ups) it answers one question: how long ago the unit's memory was wiped. Zero with an empty code list means «cleared just now» — do not trust such a car when buying: the list is empty not because there are no faults but because someone removed them.
What is normal
Same meaning as the warm-up count: it shows how long ago the memory was wiped.
These figures hold for most cars, but the maker has the last word: some engines run hotter or idle higher by design.
Step by stepHow to get ready for an emissions test in a week
How it feels behind the wheel
The same fault shows itself in different ways. Each sign below says what to look at in the live data.
Check engine came on after refuellingYou filled up, drove a few kilometres, and the light came on. The car drives exactly as before.Check engine came on after a wash or heavy rainYou washed the car or drove through a downpour — and the light came on. It often clears itself in a day or two.
How to see it
In CarScan: the Live data tab, «Start polling». The app asks the car several times per second, draws a graph and remembers the highest and lowest value of the trip.