Ok, here is the story. I bought a Mercedes SLK230 about a month ago and it has been driving perfectly but just recently the check engine light came on.

Figured with my extended warranty, I would take it to the dealership and have them diagnose and fix the issue. Sure enough; damn warranty company. Even though they told me repedetly before I purchased the coverage it's bumper to bumper warranty, they won't cover the diagnosing fee. Turns out they won't even cover the part which turned out to be a mass air flow sensor (MAF) because it's 'emissions' related. WTF!

Whatever. Different story and bottom line after speaking to a manager I requested to cancel the warranty and they will issue a refund. If I send them a notorized letter with current milage, they should pro-rate and refund. Let's see how this goes and I will updated when I get my money back.

Here is the BIG issue and bad luck. I went ahead and paid over $770 for parts, labor, and diagnosing fee to have the MAF replaced. I get the car back and am pleased. It runs great and performance seems to be back to normal. And the kicker, Less than 30 miles later, the check engine light comes on again!!

The technican, though I don't think he did the actuall service, seems like a pretty nice guy. I've made an appointment again to have it looked at again this Friday.

Does anyone have any thoughts on my situation? Am I correct that after spending $770 they should cover this, fix it, and make it right? If it's the MAF again, I'm sure they will charge me an arm and leg for other parts. Hopefully the find the root cause but what if they gave me a bad part ? Shouldn't they replace and bear the cost?

Your thoughts? How would you handle this situation?

 

Hi and welcome.

I never cease to be amazed by these stories that come out of the USA.

Firstly, is this a genuine MB USA approved garage / dealer or just a garage that covers all makes?.

I suspect the garage is claiming that "emissions" related stuff is covered by the manufacturer.
It appears you have an 8 year / 80k emission related law in the USA. and as for not covering diagnostic fees that's a straight misrepresentation / misleading tactic.
Was this stated in your contract?
If so who told you it was bumper to bumper. They misled you.
How do you fix a problem without diagnosis!!

However I'm not sure of your chances of getting anything back from MB, or whoever, is slight but its worth a try.

Now I believe the key to this is what DTC Diagnostic code was set when the CEL Check Engine Light came on.

MB garages use a system called SDS Star Diagnostics and this gives a hard copy report which should be attached to your bill showing the results of the diagnostic check and including date run, VIN (Chassis) No. etc.
This report isn't mandatory but good practice and shows that the test has been carried out.
Maybe the report exists but they don't attach routinely to your bill.
Of course some will say that it costs too much in paper and ink to do a hard copy report BUT I would read this as they don't want an audit trail!!
Non SDS systems don't always have hard copy facility.
This diagnostics test takes between 1 min (non MB system) and 15 mins (using the more sophisticated MB system). Drive into shop. Get scanner, Plug in under dash or hood. Press "test". Wait 15 secs. Read result. Print result, (Advise customer) Take car out of shop!

Dependent upon the equipment used the test can also provide you with the exact conditions under which the code was set. i.e. 4000 rpm, 100% throttle, 80 deg C water, etc etc.

So some questions?
What was the code?
What were the conditions from the flash memory?
Did the garage just reset (cancel) the code and see whether the CEL came back on again after a quick run around the block? Quite possible.

Many issues can appear to be fixed with a simple reset but come back again when the specific conditions (high revs, speed limiter, fuel grade etc etc are next demanded.
If you avoid this condition the CEL can stay off indefinitely.

Incidentally just leaving the gas cap off will cause the CEL to illuminate but this doesn't set MAF codes.

Were the parts actually changed? Evidence?
Was the new part a genuine MB sensor? Evidence?
If a non MB garage where is their receipt for the sensor. they wouldn't carry it in stock!

What code is currently set?

Now the new MAF COULD have been damaged due to oil deposition caused by other factors but lets deal with that once we have some factual evidence.

So have your discussion with the shop. Request and get an SDS report or witness the code on the reader, so that you both have an agreed starting point.
Hopefully you can negotiate to this point without additional cost or too much mistrust.

Then ask what the garage is going to proceed and how much they are going to charge.

Incidentally bear in mind that if the codes are now different that their original diagnosis MAY have been wrong.

Now, were it not for the first bit of this story, I always liuke to give people the benefit of the doubt.
Maybe these guys are entirely honourable and although they went thru the correct steps and repair they didn't get to the root cause.

On the other hand!

Come back and we will see what support we can give you once we have a bit more valiudated data.

Stuart

 

I doubt if the problem was the MAF, especially after having the same problem again, I could be wrong. but, that is a pretty dependable part. there are plenty of dishonest dealers and private shops out there. the most common cel problems are the oxygen sensor, a 002 140 68 60 valve and vacuum leaks. Check the hard plastic vacuum lines that go accross the front of the engine, they get brittle over time. Talk with other mercedes owners in your area that you run accross when you're outrunning aroundfor who they feel has treated them right.a good tech is worth his weight in your gold. Also www.alldata.com can be helpful.

 

inspect the airmass sensor for oil in the airmass. your car has issues with oil leaking into the intercooler then gets sucked up into the airmass sensor. your car might have a oil seperator which is on the top of the valve cover and it keeps oil from going into your engine. check that first.. the tech who worked on your car might not have known of this problem and just assumed it was a bad air mass.

 

thanks for the info. I hadn't heard of that before.

 

out of curiosity, is that how you know the oil separator is bad by oil in the air mass? is that the only way oil can get to the sensor? is therea waytocheck theseparator other than oil in the sensor? would oil in the sensor cause any performance problems? or would a piece of black tape over the cel solve most cel problems. I personally think the secondary air injection system is a pain in the, well neck.most of my problems I have with my slk is there.

 

Hi,

I think you mean the Kompressor rather than the Secondary Air Injection System,

The Kompressor boosts power (shoves more air into the cylinders by compressing the air).
The Sec Air Injection System injects air into the exhause manifold under certain conditions (usually cold start up) in order to "Light up the catalyst" in order to improve emission performance (i.e. reduce HC's)

Oil can get into the inlet either from the Kompressor bearings (to some extent I was confusing Kompressor with Turbo) or the closed engine breathing system. Either way oil film / dirt can coat the MAF sensor.

Normally aspirated engines (like the V6 SLK) can have oil getting onto the MAF from the kompressor because there is no compressor!! The V6 performance is almost identical to 4 cyl kompressor.

If the CEL is illuminated you have a problem which should be resolved. The car won't pass the smog test with either a CEL that is illuminated or fails to illuminate on startup.

Stuart

 

New member, sorry if I'm not using this correctly. I think I might also have a problem with mass air flow sensor. I have several codes that I'm not able to get a description on!! My car has severe power loss, checked the basics, fuel pressure, vacuum leaks, etc... (all ok) I cleaned the MAS with no change to performance. With a scanner I have one O2 sensor a little slow to respond, when I disconnect the MAS I have lots of power (more than before noticable power loss) and the transmission shifts much better (smoother) With the MAS disconnected I think the EGR is pulling open a little premature. I've seen some of these issues with Domestic cars (USA) but I don't have alot of experience with Mercedes!! Several codes that I get after reconnecting the MAS are: po9ac, p1498, p1001, pob25 Any help I could get on where to find code descriptions would be greatly appreciated. I would like to make the repairs myself and avoid the big dealer charges if possible.

 

Here is a link to some fault codes, hope this helps






http://benzobsession.com/phpbb/viewtopic.php?f=21&t=887