Changed front brake pads -- now Check Engine Light? - PeachParts Mercedes-Benz Forum

sunedog · #1 11-30-2007, 08:47 PM

99 ML 320 with 207K miles. I changed the front brake pads this evening (quickly I might add, thanks to the great info on this forum).

Started the truck up to find a check engine light. I don't have a code reader. What might this be telling me?

The only thing I can think of is something related to the wear sensor on the driver's side. I mangled the wire just a bit when installing that caliper. But I'm 99% sure I have the male end seated firmly in the connector.

PS: I got 77K miles out of the front Mintex pads. I am obviously a happy customer so that's what I bought from Phil this time as well.

G-Benz · #2 11-30-2007, 11:56 PM

I can't say without codes either, but since the check engine light comes on for emissions-related items only, that would rule out the brake components, no matter what.

The simplest symptom is the gas cap not being tightened properly. The next (and far more expensive) possibility is the MAS.

sunedog · #3 12-01-2007, 04:11 PM

I'll have to get the codes. Can't understand this unless it's just a coincidence. I wasn't anywhere near any emissions stuff. Raised the hood to unscrew the brake fluid resovoir (sp?) but didn't do anything else. Didn't touch the gas cap.

No CEL before I started. It came on when I started the engine with the front end still on jackstands. I started the engine to pump the brake fluid back to the calipers before I lowered the front end.

And I replaced the MAS within the last year with an OEM one from Phil.

sunedog · #4 12-13-2007, 12:59 PM

Was finally able to get code today. P0400. A quick search reveals (from M.M DOC) "EGR valve is defective OR that the EGR tube is plugged with carbon...OR BOTH."

Does EGR = Exhaust Gas Recirculation?

Can someone tell me what the EGR valve looks like, where it (or they if there is more than one) is located and how to clean it (if it is not obvious)? Thanks.

sunedog · #5 12-13-2007, 01:03 PM

Sorry. I just googled up this picture so I know what to look for:

Still would appreciate any insight on where it is located and how to service it.

G-Benz · #6 12-13-2007, 03:04 PM

I had to get my EGR tube cleaned on my W124 when it failed the smog test this year. Most on the forum suggested to perform this service while I had stuff pulled off during the head gasket R&R. For good reason.

My indie ignored my suggestion to this in passing, but later admitted that when he had to service the EGR, it would have been FAR easier to clean the EGR tube when the head was off because the tube is kinda buried in the bowels of the engine compartment.

I believe he had to use a coat hanger like device to get the tube cleaned out. Then recommended that I drive the snot out of the car for a couple of days in order to ensure the debris was eliminated from the system.

I'm guessing it's probably just as buried in the ML compartment...

YuCrew · #7 12-13-2007, 09:53 PM

On my '99 ML430 it at the rear of the engine...kind of a pain to remove and "snake" out....on the 430 don't damage the plastic MAF "snorkel" on the rear of the engine. If you look carefully you will see an arrow pointing in the direction of a lever that you press to unlock it.

There's quite a bit in the forum on EGR...just use the search engine

here's one link: http://www.peachparts.com/shopforum/showthread.php?p=1290750#post1290750