Help with 'Exhaust gas recirculation inoperative'

[Sinned420]

A few weeks ago I had a CEL go off on me. Checked Pin #19 and got codes 2 and 5. Wasn't able to clear them when I tried, but after trying to clear them, after restarting the car, they were gone and CEL was off.

However, few weeks later, CEL came on again. Only got Code 5 for "Exhaust gas recirculation inoperative". Same thing, tried clearing and wouldn't clear, after restarting it went away.

Came back again yesterday and now I'm concerned. I can't reproduce it and seems to happen only after the car sat for at least a few hours and engine cold.

What should I check? Wiring etc first?

[napaAl]

I pulled the EGR out of my 320, and cleaned it. A couple of flare wrenches did the trick. Probably not a fun job on a V8.

[bluerooster]

No big deal to pull the EGR on my S500. Found it to be clean, and in working order.
Checked the EGR solonoid, it's clean and in working order, Traced my particular "code 5" problem to be a bad connection on the "common" from the EGR solonoid.
EGR solonoid has two wires, one going directly to pin 39 on LH module. The other runs to a soldered junction of wires comming from several other (unrelated) modules, and controllers (I'll call that the "common" as it's common with other stuff). From that junction to a pin at the Base module. Fearing a bad LH module (which controls the EGR operation), I armed myself with a wiring diagram, an allen wrench, a flat screwdriver, an Ohm meter, and BW. Using the ohm meter, I found that the wire from the LH module, is good. (strike one for the LH module) Then I began the process of "ringing out" the other lead. I found no continuity between the egr solonoid, and the base module, But did find continuity between the other components that share the "common" connection, and the base module, as well as with each other, but not with the egr solonoid.
So my particular problem lies with the soldered connection. Which lies beneath the box that houses all the control modules, near the firewall, on the right side of the engine compartement. So I needa remove that box, to get at the connection, in order to repair it. Which I will be doing as soon as I get the chance.
But this little story is just what I've found on my own S500. your S420 may be different problem.

[Sinned420]

Thanks guys for the suggestions. I will try cleaning the valve and then check the wiring. I am not sure how to check to see if the wiring is good, what am I looking for? I'm not good with diagnosing electricals and tracing the pins etc, but I am more than willing to learn and figure it out.

Would you still have the wiring diagram? What is the LH module? I will go pick up an olm meter sometime this week after the holidays. I suspect and hope it is something simple to fix. I have the diagrams from alldatadiy and have an idea where to start.

[bluerooster]

I fixed mine today. Here's what I did:

Already knowing that the red wire with the green trace goes to pin 18 on the base module, via a common crimp/soldered connection shared with about 6 other components, all having red/green wires.
And the grey/brown wire goes to pin 39 on the LH module.
I had already determined that there was no connection between the EGR solonoid and pin 18 on the base module.

Today I decided to finish up what I'd started a couple weeks ago. I found that the continuity continues as far as where several bundles of wire all come together before entering the module box. being tight quarters I elected to not unwrap the bundle. Instead I removed the modules, the aluminum housing, and all the connectors. I found inside there, the crimped/soldered connection, that I was looking for. it had a heat-shrink blue cap on it. I had to split the cap to remove it, and gain access to the connection (first pic, cap removed).
Second picture is the culprit, singled out, I have good connection to that point. You'll notice that there is another red/green wire below the screwdriver.
That wire shares the common connection, and goes to the ignition module.
Pic#3 shows both wires, and I was tempted to just tie them together right there. But for some reason, I decided not to.
Instead, I ran a new wire, (about a foot or so) from that point to the terminus at the common connection. Just so happens that I had plenty of 18g wire left over from my last avionics install. Took my wire spoon and threaded the new wire through the grommet into the box. Made up the connection, replaced the blue cap, and added a piece of heat shrink to hold it in place. Then soldered up the connection at the other end, insulated with heat shrink tube. Buttoned everything up, and took a drive to get gas, stop at th' beer store, stop and pick up a few things at the store. All went well, ran good, and best of all NO CEL!!

[Sinned420]

I guess I'm lucky mine turned out to be this tiny rubber hose that connects to the EGR valve? There's a split in the hose right at where it bends. I'm so glad it wasn't a bigger issue.

Where would be the best place to buy this hose? I might as well replace the other one next to it too.

[bluerooster]

I usually just go to the auto parts store, and get a few feet of hose of the correct diameter. and cut off enough to hook up at both ends without kinks.
While yer at it might as well check the other vacuum hoses.

[Brett San Diego]

Originally Posted by bluerooster

I usually just go to the auto parts store, and get a few feet of hose of the correct diameter. and cut off enough to hook up at both ends without kinks.
While yer at it might as well check the other vacuum hoses.

Yeah, at this age, it's a good idea for all W140 owners to replace all vacuum and crankcase ventilation hoses throughout the engine compartment.

Brett

[Sinned420]

Originally Posted by Brett San Diego

Yeah, at this age, it's a good idea for all W140 owners to replace all vacuum and crankcase ventilation hoses throughout the engine compartment.

Brett

I agree. I haven't looked yet, but I know there are quite a few.
From the looks of it, most of them are dealer only, right?

Anyone have a complete list of part numbers for all of them? I've noticed some of mine have oil buildup around the connections.

[nathanD.rector]

I disabled my egr,don't want to breathe carbon.