Hello,

Hope everyone's week is off to a good start! I searched through the forums for days and read up on a lot of the codes but still need some help to figure out how to best resolve my current situation at a reasonable cost. I appreciate anyone and everyone's input!

I drive an 09 C63 and I recently had a CEL thrown after I was running very low on gas. I filled up at a gas station and shortly after noticed a slight vibration while idling and observed the RPM needle twitching between 500-600 RPM. I also noticed a whine coming from the engine. I took the car to AutoZone to get an OBDII read. The scan came back with the following codes:

0171 (System Too Lean Bank 1)
0174 (System Too Lean Bank 2)
0301 (Cylinder 1 Misfire)

I decided to take it into the dealership (MB W.I. Simonson in Santa Monica) to get a more detailed read using MB Star diagnostics. The scan came back with the following codes:

0636
0745 (Mixture Cylinder Bank 1 Too Lean)
2091 (Mixture Cylinder Bank 1 Too Lean at Idle Speed)
0749 (Mixture Cylinder Bank 2 Too Lean)
2095 (Mixture Cylinder Bank 2 Too Lean at Idle Speed)

The dealership ran a smoke test and determined that there was a vacuum leak from the Intake Manifold. The repair estimate was $2,400 and recommended to replace the intake gasket and bolts, vacuum hoses, intake booster adaptor and right side vacuum diaphragm. It did not list any repair for coil or spark plug related to Cylinder 1. I told the dealer the number they quoted was outrageous and I was going to take the car elsewhere to get fixed. After haggling back and forth the dealer brought the repair estimate down to $1,400.

My concerns are the following - is this repair estimate reasonable or too high? Is it an accurate diagnosis or could there be other items that might be causing these codes (MAF, o2 sensors, etc.)? Do I need to replace/repair all the items listed in the dealer quote or is that typical dealer business tactics and I only need to replace the IM gasket? The repair estimate did not include a quote for coil/spark plug replacement on Cylinder 1 - is that an oversight? Do I definitely need those replaced to resolved the misfire?

Lastly, I just moved to LA a couple weeks ago and I would really appreciate any recommendations for highly skilled and reasonably priced Indy mechanics/shops in or around LA for repairs. I have seen some recommendations in a few threads but they're further out in OC.

Any advice on where to go from here is greatly appreciated, thank you all in advance!

Without any diagnosis I would guess intake manifold gaskets with those codes as they are known to leak, not sure how DIY you are but not a terribly difficult job and parts are cheap. Others that have . done it can tell you how much time it will take. Misfire I would address the intake manifold first and see if it goes away also. The manifolds are also known to corrode and get holes in the bottom so worth checking when it is out as that can cause the lean code also - I do think 1400 is still a bit steep that is like 8-10 hours of labor. I would find a good Mercedes Indy and call and ask them how much to pull the intake and put in new gaskets.

for the items they're recommending to replace the quote is correct...

the question is...do you need to replace all of those items? additionally, there could be a possibility that an ignition coil may be faulty as well.

in all honesty...find a local GOOD Mercedes focused repair shop. my usual private mechanic employ's all ex Mercedes Technicians so the quality is actually better as generally the tech is willing to talk to me in detail which is not the case in a dealer repair shop. they only touch Mercedes vehicles. they also will show me what they see within STAR/DAS if there is ever a question and will not recommend unnecessary work if it isn't needed unless i ask. pricing is generally less than half of what would be charged from the dealer as they don't tack on additional repairs unless its 1 required or 2 i ask them to.

Hey man. Try G&N in Westwood or AE German in Santa Monica. I've only taken a Porsche to AE, but I was impressed that they were able to diagnose and fix an issue that I've had issues with for a while with another mechanic shop.

Hey roadkillrob, thanks for your note, I agree, I think the labor is a bit high so the $1,400 seems a bit pricey. Hoping to find some place less costly. I'll shop around for quotes!

Hey hachiroku, thanks for the advice and agreed on finding a good local repair shop. I'll look into the ignition coil as well. If I could get this done for half the quote it would be great!

Hey maximus, thank you for the recommendation. I went to G&N in Westwood before going to the dealer and George quoted $1,200 but the shop looked like a total mess with parts and tools everywhere and cars crammed in very closely. I checked them out on Yelp and most of the reviews were good but there were several (about 10 or so) horror stories so I'm on the fence, but haven't ruled them out yet. Have you had any work done at that shop?

Thank you for recommending AE, I'll contact them tomorrow and see what they quote me, hopefully it's more reasonable.

I have taken my AMG's to G&N for almost 20 years. I agree that the shop is cluttered, but I haven't ever had any issues. George also owns several AMG's himself, so he is a big fan of the brand. I will admit that sometimes the service is not the quickest for anything beyond maintenance-type work, but so far so good for me. Having said all that, YRMV.