Hi all

My 2004 330d m sport touring has become sluggish up to 3k rpm. Fault code P0401 (egr insufficient flow) showing in 'Torque' app.

I had fitted a k&n air filter to replace the really dirty oem, this was when the problem started.

Once I had been for a test drive, noticing the poor power delivery, I checked the ecu fault log, P0401 had appeared.

Previously, no codes were showing.

I removed the k&n and replaced with new oem, cleared the fault code log and went for another test drive. Performance hadn't improved, code reappeared.

So, removed and cleaned the maf, removed and cleaned the egr valve, checked operation (found the piston hard to open, had to use a bench vise to get it to move) and refitted. No change in performance.

On inspection, the small, blue hose going to egr offered no suction at idle.

Don't know if the k&n had any influence on the issue, maybe just a coincidence.

Anyone got any advice on getting to the egr pressure control unit? Prime suspect?

Or anyone with similar experiences?

Fingers crossed for some quick fix solution!

Cheers guys

Vacuum issue.... ALL the hoses including breathers etc should be air-tight and free from gunk internally.

Thanks dabsy, any idea on where the egr pressure control unit is? I traced the hose from the egr, it runs under the inlet manifold to the rear of the engine, but I couldn't see where it joins the pc unit.

... And thats where it is !! :rolleyes: ;)