P0508Powertrain
Idle air control — low signal
Where to start
A low signal in the idle air control circuit. Connector and wire first, then the valve itself — it often simply cokes up and stops moving. Removing and cleaning it takes half an hour and costs nothing, and the symptom is recognisable: hunting idle, or stalling when you lift off.
A code is not a diagnosis. It says which check failed, not which part to replace. Clearing it without repair only means the car will report it again in a few trips.
How to put together a report a mechanic will actually read
Step by stepUnstable idle — how to find the cause
How the code is built
Letter — the systemPowertrain: engine and transmission
Common or the maker's ownGeneric code: the same on every car
Which part of the engineIdle and auxiliary systems
Number of the faultThe serial number inside that group — it does not say how serious the fault is
All codes in «Idle and auxiliary systems»
How the app helps
CarScan reads this code from your car through an OBD-II adapter, shows whether it is active now or only stored, names the module that reported it, and puts it into a plain-text report for your mechanic.