I took my car to the dealership Monday because the check engine light went on Friday at about 5:00pm coming home from work, figures. So anyways I waited there for them to check out what was going on for about 2 hours and they told me I needed a new O2 Sensor. They wanted me to leave it there because they did not have the part in stock and they had to order. I, however, could not stay because I had class and they told me that I would have to leave the car there in order for them to order the part. I told them I was just bring it in the next and leave it in so that they can order the part. So, im getting ready to take it in on Tuesday morning and they leave me a voicemail on the telephone saying that the part came in but I would have to bring it in Wednesday(Today) to have it installed and it would be a 4 hour job. Alright that wasn't a problem I had a ride, since they never let me rent cars from there because I am underage, regardless of how many times they've told me it would be no problem getting a loaner while I was purchasing the car. Anyways, Tom the service guy gives me a call at 1:45pm saying that my car was all set and washed and ready for pick up whenever. I get on the way to go there and pick it up and while im driving back home I get on the freeway and check Engine goes on again! I get frustrated at this point and call up one of my friends that have a Engine Diagnostic just to see if he can read the code for me. Bring it over to his house and of course, it's another electrical problem, which they told me was the problem in the first place. What im asking now is, is there anything else that should be changed other than the O2 sensor that I should be expecting the service techs to be telling me need to be changed when i take it in again tommorow?

 

possible that the air filters are too filthy.. just like mine.. and my O2 sensor needs to get replaced too.. ( too lazy to do it I have everything already ) please Pm me to remind me to wash it and replace it

 

It would help if you gave us the code. I think MB is part of this big service chain mentioned in the NBC report below. Basically, they probably just reset the check engine light, didn't replace anything, charge MB (or you) for the repair, bring it in again and charge again. I had my 2002 in 3 times in 1 week for a thermostat, they claim they changed it all 3 times, riiiiight!

http://mfile.akamai.com/12924/wmv/vo...52183.200k.asx

 

I'll post my error codes. p0170 and p0173 fuel trim malfunction in bank 1 and 2.. = dirty sensor + dirty air filters. I'm gonna clean them tomorrow.. hahah lagging on it.. with the rain it's only getting worse.

 

Those are the same error codes I have. Now I know what they're gonna have to change to get that fixed.

 

I just called my service advisor at the dealership to tell him that my check engine light went on once again, and he asked me if I Refueled my car after I left. I asnwered no and he told me it probably because I didn't put gas in my car . I'm bringing it in Friday now.

 

I had those same codes.... They said I needed a new MAF. After lots of reading and cleaning of my MAF and filters without a change in the CEL coming on/off i got a new one because of their suggestions. This was an expensive adventure..

Id like to say the I still get the CEL every now and then... with the same codes and am definately less confident about my tech's ability to find the problem with the CEL....

-j0hn

 

The fuel trim codes on our cars seems to be the MAF but remember, it's just telling you that it's reached it's maximum fuel trim trying to compensate for something. That something could be a bad sensor reading like a the MAF wire getting dirty or it could be the old fashion vacuum leak so your mechanic or you maybe blaming the sensor for a real problem with the operation of your car. The most obvious way to tell if the problem is your MAF is to disconnect it and drive your car, it should be pretty close to normal (of course the CEL liht will go on but not for a P0170). If you still get a P0170 then the MAF is not the problem.

 

good point.. I realized it today when I removed everythign to clean. I havent replaced the sensor yet.. will do it tomorrow.. I realized though that the tube underneath the MAF tube was 'loose'... I made sure I secured it this time and hopefully the CEL will go out or I"ll get it reset/cleared when I get my oil changed.

 

Update...We'll I went to the dealership today and on the way there i noticed that my car was a lot more sluggish accelerating so I mentioned that to the Tech. He said he'd try and get me out of there as quick as possible and thats when my journey in the waiting room began. I was in there for 4 hours and I finally saw my car pull up so i went into the garage. The tech tells me that they replaced the O2 sensor again because the one they put in came out faulty again, but when that was done the new one also came out saying it was defective. Now he says that its my wire harness and it needs to be replaced but they do not have the part in stock and they'll have to order it. It's probably going to be until next Tuesday, and for my trouble they're gonna give me a loaner to take back because of the 12 hours I have been at the dealership this week. I'm not postive what the wire harness does, so if anyone can inform me in idiot terms id apperciate it. Then I continue and drive my car out of the dealer and to my surpise, I've never had my car run this bad in the 2 and a half years I have had it. The acceleration from 0-20mph isn't really bad but once i get past 20mph it feels like im driving a blow 1 cylinder. Its horrible, if I let go of the gas and then accel it barely even accel's, and when i floor it..o lord..I've been in faster horse drawn carriages. I'm really upset at how this has turned out so far, anyone feel that the dealer knows what they're doing?

I'm also getting the worst mpg ever. Right now im at 19.2 and I drove home 15 miles at a steady speed for the most part. It usually gets up to 28 mpg pn my trips to the dealer and back.


Side Note: One of my dad's friends is a salesman at that dealership. The Bloomfield Hills MB, and he asked me if I wanted to go to the mall while i wait for my car. I thought it was nice of him .

 

Thanks, I will try this the next time my CEL comes on.

I noticed this about the tube that is under/holding the MAF...

How 'loose' is this thing supposed to be?

-j0hn

 

Here's some help, if the O2 sensors are bad, and it would be rare that both would be bad, the car should still run fine in open loop mode where the o2 sensors are bypassed. This happens during initial warmup (because O2 sensors need time to warm up) and at full throttle. See if it runs better during these circumstances, if not then it's not the O2 sensor. Also, your condition sounds like one of two things, the vacuum leak I mentioned and check fuel pressure, it could be a weak fuel pump, clogged fuel filter, faulty FPR, hence the sluggishness and rough running at times when you have higher fuel needs.

 

Buellwinkle, Thanks I'll try that out, but i should have been more clear. The sensors were not faulty, my car was telling them that they were faulty. I'm not sure if that makes anything different.

 

Update...I just got my car back, and I'm really happy as of now(knocking on wood)...They changed the Starter Cables, Hose, and Hose Clamps...part numbers 271-150-29-33 and 271-018-10-82 and the Hose Clamp just says hose clamp....they replaced the partial load vent hose for crankcase ventilation and they also replaced the engine harness....I looked under the hood and there alot of new hoses I havent noticed before and and it looks pretty clean...On the way home acceleration was really good and my miles per gallon were still pretty low but continued to increase as I was driving. So I'm hoping it stays good like this.

On the other hand, they gave me a 2007 C230 as a loaner its really nice, but idk if it was just the car or not, but its alot slower than the supercharged 4 cylinder. Im glad i have this engine.

 

it's a v6 so it's probably a lil heavier.. glad you got your CEL resolved. I got mine taken care of as well. swapped out the MAF sensor myself and cleaned my k&n just to pass the CEL so it would pass smog.. finally got my registration tags yesterday.

 

And check that gas cap too! A lot of MB CEL's come from that simple problem.

 

And it hasn't even been a full 24 hours since i got my car back, and today while driving my CEL goes on again...I am so frustrated, what can these guys be overlooking?! I've been to the dealership a total of 5 times in the last 10 days, and it is becoming an annoyance...can the lemon law be inforced on this one?

 

Sounds like you need to take it somewhere else.

 

Check the gas cap. I had a CEL for days and the dealer was going crazy trying to figure it out. I went and got gas and as it turns out my gas cap was not on tight. I made sure it was tight and bam 5 minutes later never saw the CEL again.

 

if you didn't leave the gas cap loose then more than likely they left something loose or unplugged after replacing the crankcase vent hose. I have seen on numerous occasions where one of the other techs leaves one of the vacuum lines off on accident and the car comes right back because of it after setting the CEL again.

Take a quick look under the hood and if you don't see anything obvious then I would go back to the dealer and start mumbling things about a Lemon Law case getting started. That usually gets the ball rolling on them getting their heads out of their asses.

 

Update...I finally recieved my car back. There was a pretty extensive write up and about 20 hours of work performed on my car according to the write up. They said that the CEL light was going on because of a great deal of carbon build up in the cylinder head. They replaced my cylinder head along with my fuel injectors. Now, im not a professional when it comes to the technical side of cars, but how is it possible for that much carbon to build up in my cylinder head in a 2 1/2 year old car. On the bright side, i did recieve a new O2 sensor, wire harness, cylinder head, and fuel injectors with my 6 trips to the dealership. I hope it works out this time.

 

Dang! My Check Engine Light went on last night and i'm out of warranty (over 60k miles in 2 years). Read several threads regarding Check Engine Light and it seems like a huge hassle. Just called Mercedes Dealership and it's $115 just for an inspection!

My car runs great, gas mileage over 30 on hwy and average 26 on the entire tank, doesn't stall or hesitate on acceleration. So what could be the problem? I'm assuming it's another faulty electrical problem. Any inputs would be great because i want to avoid the expensive trip to the Mercedes Dealership. And i know that Mercedes Dealership will tend to BS about unnessary solution just to earn more$$$.

BTW, C230\PV, how is the car running now and what was the entire estimate cost to fix the CEL? Was your car under warranty?

 

I swapped out my MAF sensor, that one part costs only $110 shipped from Ebay. OEM Bosch part too. That and a good cleaning to my K&N filters and I was clear.

 

Big, you need to get the code read. If you were local in So Cal, I could help you with this. If not, go to an Autozone and ask them to pull the code. Write it down and bring it back so I can help you. I have a crazy week, but, if you PM me, I can get back to you ASAP. If I don't Mskelove (sp?) or someone else will surely be of assistance. Something tells me though, if you find your gas mileage isn't suffering, I don't think it will be a MAF code.

E

 

Thanks E!

I have a busy week as well. I'll be out of town tomorrow night and will return Sunday night. I'll visit autozone early next week and i'll PM you the code. I highly doubt anything is wrong, probably a stupid electrical problem. Again, it doesn't hurt to check but the last thing i want to do is pay a visit at the dealership. They BS all sorts of things just as any other dealerships.

But for the past 150 miles, everything seems normal; gas mileage, acceleration, idling, start up etc.