PID 2C%
Commanded EGR
How far the unit asks the exhaust gas recirculation valve to open.
What is normal
Usually zero at idle and at full throttle: recirculation is for the middle of the load range.
These figures hold for most cars, but the maker has the last word: some engines run hotter or idle higher by design.
Codes about this parameter
P0400Exhaust gas recirculation (EGR) — malfunctionP0401EGR flow insufficient detectedP0402EGR flow excessive detected
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
Codes behind this reading
If the value is out of range, the unit usually says so with one of these codes.
P0400Exhaust gas recirculation (EGR) — malfunctionP0401EGR flow insufficient detectedP0404EGR valve — position out of range, sticking
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.
The temperature gauge is climbingThe needle goes above its usual place, there is a hot smell from under the bonnet, and the heater may blow cold on a hot engine.Idle speed huntsThe tachometer needle wanders up and down with the car standing still: 1200, then 600. Sometimes the engine nearly stalls and picks up again.It stalls at idleAt the lights, or when you lift off, the engine dies. It usually restarts straight away.
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.