W203 Fault code P0400
Thread Starter
Junior Member
Joined: Nov 2012
Posts: 16
Likes: 0
From: Northern California
2002 C320 Wagon 200k miles
W203 Fault code P0400
Hello Everyone.
Love this site. I've managed to repair several issues from advice gleaned from some good people on here.
I have a 2002 C320 (135K miles) with the P0400 code showing up and I was wondering if you can recommend a process of repair through elimination ?
The engine runs no problem, but I 'think' I notice a small difference in that I sense that the motor is a little rougher, if that you get what I mean.
I've seen some reference to cleaning pipes, checking for small hose leaks etc....but is there something (or a few things) you know of that I should be looking at specifically and in what order ?
Dont mind DIY at all, but some guidance would be appreciated.
thanks.
Love this site. I've managed to repair several issues from advice gleaned from some good people on here.
I have a 2002 C320 (135K miles) with the P0400 code showing up and I was wondering if you can recommend a process of repair through elimination ?
The engine runs no problem, but I 'think' I notice a small difference in that I sense that the motor is a little rougher, if that you get what I mean.
I've seen some reference to cleaning pipes, checking for small hose leaks etc....but is there something (or a few things) you know of that I should be looking at specifically and in what order ?
Dont mind DIY at all, but some guidance would be appreciated.
thanks.
Super Member
Joined: Jun 2005
Posts: 651
Likes: 5
From: So. Cal.
'02 C320 Wagon, '78 308 GTS, '06 Highlander Hybrid
Funny you should post this...
My CEL just came on about a week ago with the same code. I too have an '02 C320 with almost identical mileage (140k). LMK what you come up with. I think the first step is to clean the EGR valve. If that doesn't do it, then I think we're looking at replacing it.
My CEL just came on about a week ago with the same code. I too have an '02 C320 with almost identical mileage (140k). LMK what you come up with. I think the first step is to clean the EGR valve. If that doesn't do it, then I think we're looking at replacing it.
Thread Starter
Junior Member
Joined: Nov 2012
Posts: 16
Likes: 0
From: Northern California
2002 C320 Wagon 200k miles
I guess it's about that time & miles for EGR valves.
I am hoping someone can post some directions on cleaning the valve.
A little guidance would give me the confidence.
If you find anything, LMK pleeeeease.
cheers
I am hoping someone can post some directions on cleaning the valve.
A little guidance would give me the confidence.
If you find anything, LMK pleeeeease.
cheers
Thread Starter
Junior Member
Joined: Nov 2012
Posts: 16
Likes: 0
From: Northern California
2002 C320 Wagon 200k miles
Just found this forum thread with diagrams and some 'how to'.
https://mbworld.org/forums/m-class-w...uess-help.html
See username: 'Maj Dundee' who has posted some pdf diagrams/images of EGR Pipe that everyone says needs cleaning.......
I'm going to try and do it this weekend. Fingers crossed.
https://mbworld.org/forums/m-class-w...uess-help.html
See username: 'Maj Dundee' who has posted some pdf diagrams/images of EGR Pipe that everyone says needs cleaning.......
I'm going to try and do it this weekend. Fingers crossed.
Junior Member
Joined: Apr 2013
Posts: 18
Likes: 0
2007 C230, 1995 C280
I have a '95 c280 with a recurring P0400 code. EGR valve and charcoal filter replaced and vacuum lines cleaned out along with "ERG looking device" in front of EGR cleaned out also. CEL can be reset and will stay off for a month ot more before coming on again. My factory trained tech is at a loss and even suggested taking the car to the dealer and let their dyno-tune guys diagnose the problem. Anyone have any suggestions? Engine runs like a champ with great gas mileage(134k).
