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.

__________________
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.

__________________
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!

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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