P0506Powertrain
Idle speed lower than expected
Where to start
The idle speed is below the target and the car may stall. Start with cleaning the throttle body and checking that the throttle cable is not sticking. Also look for a lean-mixture code nearby: an air leak produces the same complaint.
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.