E90 320d Smooth running fault code 4b10

This fault code relates to adaption values of the car and can reduce MPG, a simple code clear can sometimes rectify this, essentially removing the adapted values and resetting the ECU.
If the code re appears, because smooth running correction is adjustments between the injector quantities to keep the engine running smooth, it can tweak the fuel quantities between the individual cylinders to keep a good average and smooth running.
In this case, is it pointing to the adjustments needed are too big for it to cope.
Glowplugs can cause this, along with dirty injectors.

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