P0401Powertrain
EGR flow insufficient detected
Where to start
Insufficient exhaust gas recirculation flow. Usually a passage or the EGR valve clogged with carbon rather than an electrical fault. Cleaning solves it more often than replacement.
What to watch in live data
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 thisP0401: the EGR valve is cleaned more often than replaced
Step by stepHow to check the EGR valve with live data
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 engineEmission controls: catalyst, EGR, fuel vapour
Number of the faultThe serial number inside that group — it does not say how serious the fault is
All codes in «Exhaust gas recirculation (EGR)»
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.