Cel 2-4-1
 

Hello all,

I have a 1991 740 T w/181k. Every now and then as of late, the CEL is coming on, only if I start and go w/o waiting for a couple of minutes for it to warm up. Yesterday I checked my code reader on the strut tower in the engine bay. I got 1-1-1 on pin #2 and (so no codes) and 2-4-1 on pin #6. I referenced this link, https://www.volvoclub.org.uk/faq/Eng...agnosticCodesi, and it states it could be EGR valve, EGR wiring, EGR vacuum or controller or EGR temp sensor. Any one have any thoughts please let me know. Car runs fine.

Thanks,
Mike

Well, EGR faults are indicated. Could be the valve itself not holding pressure, or associated plugged piping.

classic test is to disconnect the hose from the EGR control valve to the EGR itself, hook that hose up to a mity-vac, with the engine idling smoothly, pump a bit of a vacuum, the EGR valve should open and cause the engine to stumble and stall until you release teh vacuum.

if it doesn't hold vacuum, your EGR valve diaphragm is shot or the hosing is shot. if it does hold vacuum and the engine stumbles, then the EGR valve and plumbing are good, so yuour problem is upstream with the control valve. if it doesn't stumble, then the EGR plumbing is probably plugged up, usually at the intake side, rooter it out with a steel wire

OK thanks pierce and lev, I think I will run a wire through the hose just to see if it helps or is clogged. I would assume it has gunk in it after all these years, just as the diaphragm could be bad as well. I looked at it and the hoses and looked ok, no cracks etc.I am going to have to apply some PB Blaster to the fittings for a few days before I attempt to disconnect it, they looked happy to be where they are, not to rusty at all though.

So I disconnected the vacuum line off the EGR and reinstalled with the spring clamp rotated 45 and..no more light! I suppose 28 yo hose can have some air leak around a clamp. It was pretty loose, and moving the clamp tightened it up. If it comes back I will have to disconnect the hard line and run a wire through them.