Blackvan

Hi everyone! hope all good with you guys!

Brief history: I just bought a W204 C300 2012 model a month ago I was aware of some minor issues like seats torn, scratches etc and I'm aware of having a "check engine light"with a of Code: 0942 & 0946 at first!

Now I have done PMS (Service B) as soon I got the car except for the Transmission oil change which I'll be dealing next.

Here's the scenario now, I'm already using it for awhile now, I was on a 60km trip testing the gas consumption on ECO mode and pretty happy with the results BTW! Then when I reached my destination I just notice my check engine light is gone! Happy at first but need to double check it so I scanned it with my ThinkCar dongle tool and yes theres no major one that can trigger the check engine (as far as I know please correct me if I'm wrong) but..... see some fault codes like for the side lamps which I know already, and there's some Fault codes also at ECM - 1304, 0632, 0656, 0942 & 0946 but no check engine lights.

Guys BTW I dont feel anything strange about the car it runs smoothly. No misfiring etc not even a bad smell on the exhaust.

I'm not yet done fixing everything but just wanted to know if is it normal that the check engine light goes off but still having these faults codes?

I'll attached the results



Thanks in Advance Guys!

JettaRed

iTrader: (1)

It's best to delete/clear the STORED codes and see which ones return. Then begin troubleshooting based on the new codes.

Whatever was causing the CEL is no longer present and after several drive cycles, the light will turn off, but codes remain as STORED.

TimC300

When you mention going for a long drive and the check engine light turning off I immediately thought of codes for the cats, and seems my assumption was correct.

I would just erase the codes and drive the car around on the highway. I recently had my car in the shop for over a week and when I got it back it was running rough where I thought something was wrong. I went for a long trip and sure enough it smoothed out and seems to run perfectly now.

Unless you have the records of all the work done to it i would go thru the maintenance manual and make sure everything is up to date, like spark plugs, air filter which you may have just done, etc.

What engine do you have, M272, m276?

I like putting a bottle of Techron in the gas tank twice a year. I dont always fill up with Tier1 gas so maybe thats why I do seem to notice a positive effect after using it. It does seem to smooth out the engine if its running rough at stop lights and at idle. Just recently I was ready to go buy a bottle but like i said the engine seems to smooth out on its own.

In a nut shell erase the codes, drive the car, and see what if any codes come back.

Blackvan

Thank you! @JettaRed Appreciate it! will do that now. I'll update and share it as well what will happen next.

Blackvan

Thank you @TimC300 Yes you're right! The previous owner actually declare that it was the cats as he mentioned before he changes the exhaust, actually when I check it before it was just a CATBACK exhaust and everything was still on stock but still maybe there's still some prob with the cat due to age.

This Car has been all over the places now. It's a US specs from East side then was on Coparts Middle East. The previous owner got it last and rebuild the neccessary works needed. I just want to continue what he started.

BTW Guys really loving it now it's my first Merc! Hoping to fix everything soon and have more experience in German cars.

For the engine part I think M276 as he mentioned its a 2012 and 3.5L (Im not really sure how to check it)

Thanks for the help guys! Appreciate it!!

Blackvan

Forgot to mention just to be more detail

I have changed
-Engine Oil (merc)
-Brake fluids
-Coolants (merc)
-Air filters (Mann)
- Oil Filter (Mann)
-Checked brake pads (I think need to reface the front disc)

Next will be Transmission just finding some garage whos expert in Merc I'm thinking to totally drain it including Torque converter.
Check all suspension and under chassis bushings

This is my daily car now with 60 to 70km daily route.

JettaRed

iTrader: (1)

If the car has a 17-digit VIN, you can enter it a www.lastvin.com to see how the car was originally configured from the factory.

TimC300

I recently checked and cleaned the pads and rotors. I have the drilled rotors in front and just stuck a drill bit thru to unblock the holes, no drill.

I had replaced everything when I got the car and now a few years later everything still looks good but I can tell I will most likely just replace the rotors again when I do the pads due to some grooves appearing. I have Zimmerman rotors and the min thickness is printed on them if someone wanted to measure. Probably more cost effective just replacing for the low cost of the rotors. Pads I used Ferodo in the front and ATE in the rear, just the regular semi metallic. They throw out brake dust like crazy and im always cleaning the rims, but I think its worth it for how good they stop the car.

I cam across some useful info on checking the rotors. Rotor thickness appears different depending on which ones are installed.

Blackvan

Thanks for this @JettaRed Now I'm confuse Lol so I found out that its C280, is it same with C300? saw the engine is M272, I'm just a little scared that these might have the common problem before about the balance shaft gear.


Anyway will still rebuilt this amazing car I done some deep cleaning today and buffing. Thanks guys!

Blackvan

Wow! Thanks @TimC300 for this! will do this next for sure. It's better to start the safety as well as I'm always with my kid. I have checked the my FR RR pads still in good shape but front disc I guess really need to do some works.

Blackvan

Guys I would like to share this as well as I'm having a hard time to find this part

Fuel Hose

I think it's a Fuel hose going to Injectors. I saw some moisture not actually a leak.. I tried to search here locally (U.A.E) but store doesn't have it, I'll try to find it in a yard next time or better yet to take it in EBAY.
Does it trigger CEL as well? This might be the one if so.

What do you think guys?

TimC300

I would just clean the hose and monitor it. Throw a wrench on it and make sure its tight. You would probably smell gas if it were leaking. Spray some soapy water on and check for bubbles. But I think its just dirty. If it were leaking you may get a code for low fuel pressure. be careful if you do replace it, release the pressure on the fuel rail, you will see a shrader valve on the opposite diagonal side of the rail.

its part# 2044700675.

I have my DA polisher out today, fixing a few scratches before I seal the paint for winter. I use meguiars Ultimate Compound which seems to work nicely, though it takes forever. Its probably good since its hard to mess up and ruin the paint.

TimC300

Whenever i have the air box off I throw a clean microfiber towel over the open MAF, make sure it doesnt get dirty.

I rub a tiny amount of silicone grease on the rubber seal on the air box, also coat the knubs the air box clips to.

JettaRed

iTrader: (1)

I'm guessing the car was debadged. The complete readout from lastvin will tell you the actual engine size toward the end of the list. Look for code M30 or M35 or something close to that. I think you are OK regarding the balance shaft issue.



https://eeuroparts.com/blog/mercedes...04%20to%202008.

Blackvan

I did check it last time when I change the spark plugs, I was tight actually at first when I got the car it smell I tiny bit but when I changed the spark plugs yea didn't smell any, but will still check.

Nice to hear that you've done some polishing, I did it as well this weekend and trying to bring back the true colors and yes still achieving it except for the front bumpers. (I'm just celebrating the 'NO CEL' Lol)





Hope you guys had a great weekend!

Blackvan

Wow it was a little relief knowing that its not affected. BTW here's what I found out


M30


Still good right?

Thanks for sharing the link