Is it safe to drive with a CEL P0400 for a while
 

Hi,

my 1996 E320 (W210) is throwing the CEL. I scanned the code and got P0400 indicating EGR Malfunction. I did a search and many posts suggest to try cleaning/replacing the EGR pipe, what I find difficult according to the posts.

My question is: Can I continue driving the car for a short time without damaging the engine until I get it fixed?

Thanks!

A malfunctioning EGR will raise your exhaust emissions ( NOx ) somewhat and may also reduce your ignition timing advance.
But nothing serious enough to jump off any tall buildings. ;)

If I have to get parts for replacement it will take a while, good to know that it's OK to drive a few days with the defect. Thanks manny!

I would diagnose it before doing anything.
An EGR code on that chassis can be anything frrom the common crossover vac line cracked going to the EGR SOV to a blocked tube at the head, or anything in between.
A simple hand vac EGR activation test should be performed at idle.

Thanks Mr. Dalton,

I'll take the car to my Indy and have it diagnosed soon.

You may want to try a simple test yourself..if so inclined.

There is a vac line that goes to the EGR and if you take that line off and pull a vac on the egr with a hand pump at idle , the engine should sputter , run rough ,and almost stall.. If it doesn't , then you know the tube is blocked.
[ infamous problem on 104] .. but if it does , then the suspect is that vac is not getting to the egr and on a 104 that is usually just a broken white plastic vac line that runs across the front of the engine [ under that front plastic cover]..notorious fault b/c they crack from heat fatique and then the EGR can not open b/c of no vac, thus setting the code.
The simple fix for that is to just to replace that plastic line with a generic rubber one.....a $2 DIYer fix.

Something to check before going intp the Hospital for Surgury..

In many other posts a tube is mentioned that is not easy to access.
If the clog in one of the two parallely running white plastic tubes in the pix below I'll try it this evening. Thanks a lot!

http://s245.photobucket.com/albums/g...nnotated-2.jpg

PS. the dirty brake fluid in the pic, which Mr. Dalton drew my attention to sometime ago, has been replaced :)

The tube that is not easily accessed is not the vac hoses in the front of the engine.
That tube will be a large metal tube/pipe coming from the EGR and going to the intake at the head and it goes across the the rear of the engine..They block with carbon where the tube meets the head port that the egr gases flow through.
The vac hoses in the front of the engine do not block up, they crack or split open and they only transfer vac supply to operate the egr valve..different hose altogether.

I am going to check the easy thing firstö Hope it is not the tricky metal tube. Thanks for taking the time to explain.

The hand vac test is to tell if it is the metal tube. What you are doing with the applied egr hand vac test is you are taking all the other parts to the egr system out of the equation and you are literally operating the EGR valve MANUALLY..

To my surprise the CEL is gone after I left the car unused for a day. I scanned the OBD II codes and there is none. I have done nothing except taking a look under the hood.

Now I am confused, was it a temporary issue or a quirk in the electronics or self-healing EGR?

Anyway

I took care of it ..... :)

Most like suspect would be a sticking EGR ..just keep an eye on it ..the code cleared itself b/c ithas not seen any repeats.