Hi guys: I'm trying to get my sister's c-280 smog-certified so the registration can be renewed again. When i took it to a smog test center, they did a pretest and the smog emissions passed, but the check engine light failed to go off after the car started. He suggested that i send it to the dealer to have it repaired before getting a test only center to run the test again. He also mentioned that i should replace the gas cap. Although i'm not quite sure how that'll help in improving this car's smog emissions, but i guess i'll have to give it a shot. P.S. does anyone know what an EGR is and what it does? Is it hard to replace? Expensive? TIA! Mars

A loose or defective gascap can cause you grief, i.e. CEL.
As far as the egr valve goes, do a search on " cleaning egr ", or " exhaust gas recirculation valve".
They do have a tendency to plug up, which does NOT necessarily mean the valve needs to be replaced.

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2007 C 230 Sport.

Get the codes read .
If I were to list the number of faults that can trigger a CE lamp, my fingers would hurt.....

Yes, do that as well.

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2007 C 230 Sport.

Since your post suggests an EGR problem... P0 400 on that car..

Here are the posibilities:

The EGR valve doesn't open...doesn't hold vacuum...doesn't get vacuum.

The vacuum switch-over valve doesn't have a vacuum source....doesn't get signal to open.. doesn't open.

The EGR tube is PLUGGED or partially plugged.......THAT is the most common EGR problem IF the above things pass first!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
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Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Wow.... very impressive indeed. Thanks so much for the valuable info. My local smog station did a pretest and the car did pass the test. But he did insist that in order to pass the full test i'll have to get the check engine light looked at and i'll also need a new gas cap. The egr and check engine light problem was both discovered by the dealership last time this car was in service.

hmm.... I just rechecked the log notes on the dealer service receipt from last time, here's what it said:

"client states that the check engine light is on (on or off) egr malfunction. checked for codes. found p0400 egr flow malfunction. ck egr system, valve and vacuum to egr valve are normal. found no rpm drop when activating egr valve, egr tubing is cloged at intake manifold. need to remove tube and clean. cleared code for time being. client will address later."

Looks like you were dead-on about the egr problem, doc. My question now is: will i be able to clear up the tubing myself? or should i leave this job to the professionals?

Thanks again to everyone for their helpful inputs!!

Mars

WE always replace that tube...modified version goes farther into the intake..doesn't clog as quickly.

They can be cleaned BUT codes will come back QUICKER.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Just got a quote back from the dealership. To replace that tube it'll cost me around $600~$1000 big clams. Ouch!

Does the air intake manifold have to come off on some of the M104's to R&R the EGR pipe?

My car's throwing EGR codes also, and it looked to be a simple job, but then I read postings that talked about removing the manifold to get to the end of the pipe. Is that only for the later versions with the longer tube?

__________________
--
Steven Harrison

1993 300E2.8 - 196K
2001 E320 4MATIC - 86K

Since the intake has 2 parts ONLY the upper section has to come off.

AT dealer the labor should be 3.2 hrs X rate.

The parts list for approx $160..

Iwould think that approx $500 would be a "HIGH" end price.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Wow, that sounds like a good deal. Too bad you don't live in southern cal, doc. Otherwise i'd love for you to work on my car. $500 will be a great deal compared to the ripoff quotes i'm getting.

Maruzo,

Ask your service advisor for a breakdown of what they want to do for their $1,000. My dealer is happy to show me what he wants to do and how much the parts and labour cost - when I had major maintenance due last year, he broke down what would cost what, and it allowed me to pick and choose what I would do myself (fan bearing bracket & wiring harness) and what I'd let him do (head gasket).

If he won't break it down for you, find another dealer that will.

__________________
--
Steven Harrison

1993 300E2.8 - 196K
2001 E320 4MATIC - 86K

ok... further bad news. The check engine light went away today... completely. It doesn't even light up with the key in ignition. Took the car to smog check station again because with the check engine light completely gone after the car has started, i thought i might get a low flight by below the radar of smog test stations.

Alas, it was not so. The smog station found that the check engine light doesn't even light up during ignition. So i got a failed receipt. Replaced the gas cap and took the car to the dealership today. The service advisor wants 3 hours just to diagnose the check engine problem. And then whatever needed to be done to repair the light will then be added on. This really pissed me off. I mean, the car passed emissions, the only thing i had to do was replace the gas cap and get this light fixed. And now the service wants another 5~600 bucks to look at the darn light? Plus on top of the light i still had the egr tubing problem to fix.

One thing i did notice with the instrument cluster was that the speedometer and the rpm meter stays at 0 when the car first started. The needles doesn't start working until i've driven the car for at least 5 to 10 minutes. The bad bulb light also has come on, and then the light on the outside temperature indicator has become dim.

Not sure if these are tell-tale signs of a bad cluster board of whatnots. But thought i'd post it to see if any m-benz gurus might've encountered it before.

TIA!

Mars

OK, an interesting update:

Took the car to 2 different dealerships for a quotation on the missing check engine light. First dealership (located in the downtown area) wanted $250 to look at the problem. And that's not including any work they might need to do once they found the problem. Second dealership gave a flat quote of $120 to check the problem, and the service advisor gave a detailed description of what they'll do: take off the steering wheel, remove the instrument cluster, and check n see if the bulb has burnt out.

Left it at the 2nd dealership, and the car was repaired next day with a working check engine light. And this time, the light went off after the car started!!

Yeepee!! Took it to the smog station and had them promptly retest the darn car. This time it passed with flying colors. The dreaded egr problem didn't even bother to show up this time.

Looks like i'll be able to certify this old gizzler for another 2 years!

Peace out!

Mars

Good stuff.
So what exactly did the dealer do to make things right ?

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2007 C 230 Sport.