PID 30
Warm-ups since codes cleared
How many times the engine has warmed up since the codes were cleared. A warm-up means a full cycle: cold, then hot. The number matters before an inspection: some self-tests run once per trip, so until enough warm-ups have passed, readiness will not be set no matter how much you drive. PID 31 and PID 4E count the same thing in kilometres and minutes.
What is normal
It grows with every trip. A small number together with «monitor not ready» points to a recent reset.
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.
Slow to warm up, the heater blows coldThe temperature needle sits low for ages, the cabin stays cold, and on the motorway it gets worse. Consumption rises noticeably.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.