320GLCDI2008

2008 GL320 CDI
I started getting a check engine light with Code 0672 for No. 2 Glow Plug circuit, replaced the glow plug, it would clear for a short time, then come back on with the same code. I took it to MB Dealer (ParkPlace Motors in Ft.Woth) for diagnosis the Tech said the code was because I didn't replace it with a "Mercedes" Glow plug, (didn't bother trying to diagnose it), so I bought and installed a glow plug from Mercedes (both the OEM and the one I bought were manufactured by NGK and had the same part no.) took it back and they cleared it and it came back on after less than a day.
(So much for the B.S. Non OEM part theory) I did demand my $190.00 diagnostic fee be refunded and it was.
Anyone have a similar experience with this code or have a recommended solution? Or know a REPUTABLE Mercedes specialist in the Dallas/Fort Worth area? (ParkPlace Motors of Ft. Worth is NOT recommended)
Any help/advice would be greatly appreciated.

N_Jay

I would guess that if it tells you the same glow plus is bad twice, it is probably the wiring or the controller.


You could swap the plugs between cylinders and see if the problem moves.

320GLCDI2008

Thanks, I've been pouring through some of the old posts and it seems that the controller could be giving this problem although the code isn't specifically for the controller. I was able to find one for around $144.00, I'm going to give that a shot.

N_Jay

If you have the original controller, it seems it is overdue to fail. The replacement is an updated part.

AnchorMgmt

My #5 plug was replaced in Dec. I got P0675 regarding #5 plug the other day. Part was under warranty so I had my trusted mech swap it. It immediately threw same code again. He suggested it was the controller. My part will be in early next week and I hope it fixes it as well! It's rt on the front of the motor so it'll be any easy plug n play swap. Good luck 2u.

N_Jay

Seems like a lot of '08s have the controller fail over the least year or so.

AnchorMgmt

Add the differential pressure sensor at the dpf to that list!

N_Jay

Have we conclusively found that to be the cause of our random limp mode issues?


Mine has been fine, but have not taken a long drive in wet weather yet.


I am starting to think it is a water problem (Maybe water getting into that sensor or its electrical connection.)

AnchorMgmt

It seemed most of us had the DPF sensor issue during the extreme cold of this winter...I live 80 miles due south of you so we endured the same nasty winter! My local MB mechanic said the other GL320 that had the same issue had not been back since Jan when he had replaced it. I've been good to go for 8k miles too. I never had this problem in 88k miles/3 years when I bought my ML320 back in 08. Time must be a factor too.

At least I can always count on my Kubota tractor w/3 cylinder diesel to start and snow blow all winter with nothing more than getting cold b/c of no cab!

It's suppose to be a soaker tomorrow so we can test our rides out!

Benz2008

I got the same issue with Code P0672 Check Engine and glow plug stay on after engine started for about 1 minute. Fort Worth Mercedes Benz dealer said it is 2 glow plug is bad. Also took it AutoZone to read the code. it's said the same thing number glow plug is bad. after reading many post from this site, I decided to change out glow plug controller and I bought it part.com. It fix my issue, no engine light, no glow plug light. It fixed my issue. The engine light went away after a week of driving.

bha

Just for the record, the last 4 posts I have read about a glow plug code (glow plug bad) it has turned out to be the controller and NOT the plug. I don't think I've recently (within the last 2 years) actually heard of someone replacing a glow plug.. but lots of controllers.

You will find when replacing the controller that it has been updated and looks a lot different than the original.

I hate to recommend throwing unnecessary parts at the problem, but at this point I'd recommend replacing the controller FIRST when you get a glow plug code. In my opinion, it's most likely the controller (water leakage inside?) and not the plug.

Just some food for thought for anyone who runs into this in the future. Even if the glow plug does end up being the problem in the end, your controller was probably overdue for replacement and was going to fail shortly anyhow...

joshd2012

Thanks for the post. Interestingly enough, in the rain this morning (someone mentioned wet weather above) I had the preglow light stay on after startup. That happened once more in the morning, and then tonight I got a CEL. I will be sure to have my mechanic test the plugs before replacing and suggest it's the controller.

alx

it is always the controller. i have never seen a plug go bad.

joshd2012

Well, you can put me down as the first.

The controller was bad, but when the tech took readings of the glow plugs, the one that threw the CEL was 1.6 Ohms and the other others were all between 1.2-1.4 Ohms. Since none of them matched spec, they are going to replace them all as well as the controller. I got to check my extended warranty, but I don't recall any of the diesel specific parts making the list of covered items - this looks to be another $800 invested in this truck.

N_Jay

I would do the controller and not the plugs unless I got another error.

marc hanna

Glow plugs do indeed go bad. It's worth while swapping them out every 100,000kms or so even if they're not bad because they can get seized in the bore, and then it's a bit of a bugger to get them out.

bha

I have heard that they are difficult (or impossible) to replace if you wait too long. Apparently they can snap off when being removed which causes a huge problem. There is a special "reamer" tool from MB that is used to clean up the gunk once the plug has been removed.


However, I bought my truck with 170,000km (now has 275,000 or so) and decided that it was probably too late to start removing glow plugs when I bought it. So I left them and they have been fine. Don't know what I'd do if one failed now

sak335

Rather than replacing them, if the issue is that they seize in the bore, would it not make more sense to R&R at the appropriate mileage, and perhaps put some anti-seize on the threads?

N_Jay

The question would be, "What is the appropriate" mileage to crack them loose for safety, and what is the risk of breaking a good one if you are past that mileage?

Form what I understand, it is not eh threads that bind, but rather down the shaft towards the combustion chamber.

Given the pressures in a diesel, I am not sure anti-seize would do much good. (I think it is an issue with carbon forming between the plug body and the bore.)