P2187Powertrain
System too lean at idle (bank 1)
Where to start
Lean only at idle — a very telling sign of an air leak: at speed the extra air is lost in the total flow, while at idle it stands out completely. Look for cracked hoses, the crankcase breather pipe and the throttle body gasket.
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
We have a detailed piece on thisLean and rich mixture: P2177, P2187, P2195 vs P0171
How the code is built
Letter — the systemPowertrain: engine and transmission
Common or the maker's ownGeneric code, second group
Which part of the engineFuel and air metering
Number of the faultThe serial number inside that group — it does not say how serious the fault is
All codes in «Mixture: lean and rich»
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.