EGR Bypass and Engine Management Light
 

Well, the title says it all.
I removed the EGR and fitted a bypass which worked really well ... when two days later on the M25 the Engine management light came on and is staying on :(

1. I'm guessing it has something to do with the EGR as the car didn't dramatically stop/overheat etc, but no idea how to find out for sure.

2. If it is ... any idea what I can do about it short of cleaning the EGR and fitting it again?

I suspect the light will go out again, make certain the braided pipe is on the bypass securely.

if it took 2 days for this to come on I would hazard it is not related...
You can check all connections to the MAF, MAP and the vacuum hose being in place as stated, but I can not see an EGR bypass causing any issues re overheating etc, at worse you could lose boost pressure if fitted poorly...

what year is your car, have you the intake air pressure sensor in the top hose, is the plug secure?

Have same problem light comes on approx 300miles sometimes goes out by itself always same fault code everything in place and tight been doing it for about a year no other problems car performs like a dream just keep putting the light out

It's an 04, with everything tight and fitted correctly.
However ... I've just filled it with Diesel, shoved a bottle of Redex Diesel Advanced Fuel System Cleaner in it (I was hoping the EGR Bypass would stop the plume of black smoke under heavy acceleration, it didn't, so I thought I'd see if this stuff worked). And ... Engine management light has now gone off. #confused

Did you clean the inlet manifold and MAP sensor out when doing the EGR bypass. With all the crud in there it will still smoke, if not more so.

Craig

Well,
Phil did the T4 on this (mainly to do the cruise control) and found it was coming from the MAF sensor.

I cleaned this when I did the bypass, so I guess if the light comes on again I will do a re-clean/check connections.

MAF or MAP sensor ?

If its the Bosch MAF I recall it being quite delicate; so not exactly sure how you would clean in easily; don't scrub it!!

However if you have added some new fuel and a combustion enhancer/cleaner and its gone out I would say that it is likely that using it will make it improve. What type of driving do you do most shorter trips by you or previous owners will have left allot of black **** everywhere. Its incredible how much black soot builds up. On my Tourer it was only after I had cleaned everything, removed the cat and a full stainless exhaust that it stopped puffing like an old chimney!

If performance and fuel economy is still excellent I would say its not likely a faulty MAF.

Other sources of black can come from the O rings on the turbo pipework being faulty too.

It wasn't the MAF sensor, it was the T21 Temperature sensor in the intercooler pipe.