SLK Power Loss/Starting Problems

08-24-2005, 01:39 PM
Hey Everyone:

I could seriously use some help. I have a 2000 SLK with about 66k miles on it. About 7000 miles ago, I started having some odd starting/stalling problems, that have gotten progressively worse.

The first sign was when the car simply did not start. I was about to take a long trip to Northern Cali and it kind of freaked us out, but then after a few minutes it started and drove all the way up north (500 miles) with no problems.

On the way home, after driving a long ways (250 miles or so) and getting low on gas, the engine light came on and suddenly the car starts decelerating and the engine seemed to shut off. I had to muscle it to the side of the road. I tried to start it and there was nothing - as if the starter was broke - no turn over at all. Waited about five minutes and it started up and we were on our way again, making it the rest of the way home - 100 miles or so.

I talked to my import mechanic and he changed the starter, which I think now was a complete waste of time. He also suggested that it could have something to do with the amount of fuel because if it is low on gas, the fuel is used to cool the pump, and the pump could be shutting off because it is getting hot. I don't know if this is correct or not, it is just what he said.

I started keeping the fuel above 1/4 tank, but it did not matter. The car continued to do the same thing but progressively worse, but I noticed that it always seemed to do it when I was below half a tank - not a quarter tank. So I started refilling it before it got to half a tank. This actually did seem to help and I didn't have any problems at all for a month.

Of course, I'm writing now because all bets are off. Recently, with almost a full tank it died after driving ten miles. It did start up again, but only made it about a mile, and died, then a half mile and died. At which point I had it towed back to my import mechanic. He checked the codes and said that the only error showing is "long term fuel trim too rich." Frankly, he didn't seem like he had the slightest clue what this meant and he basically has told me I should take it to a MB dealer. I'm wondering if there is something in the mb computer that, causes the car to shut down when the average fuel trim richness exceeds a certain number?

This might explain why I went a month with no problems because, prior to that time I did not drive the car for about three weeks because of the problems. So maybe letting it sit for a long time (as opposed to keeping the tank over 1/2 gallon), caused the fuel trim measure to be lower long term which kep the car from shutting off, but having been driving it a lot lately, the computer measure for long term fuel trim is showing it too rich again, which is maybe causing the engine to shut off. Of course, I have no idea - I'm just guessing.

On the other hand, it seems like it could have something to do with temperature, because once it sits for a few minutes it will start up and run like normal - but only until I drive for a while and it heats up again. But if it is heat, what is heating up? The engine is definitely not hot when this happens. Also, it seems like if it was just the temperature, then it would have always been as bad as it is now.

Has anyone experienced a similar problem with the SLK series or any MB? I would prefer to have my mechanic replace something that is the likely cause than take it to an MB dealer and get screwed for a bunch of money on "evaluation."

Thanks for you your help.

04-07-2006, 01:42 AM
Sorry to hear of your problem. This week I experienced somewhat the same thing - twice.
Driving along, one by one each light (SRS, ABS, etc) went on, and then lost power, give it gas, was going nowhere. Pulled over. Battery dead. Wait a minute, starts for a bit, then dies again. Tow to garage. Assume it's alternator not charging battery. Replace alternator and battery.
Next day, Everything ok. Drive 150 miles to OC.
Nighttime return, same thing happens. One by one each light comes on, car decelerates, giving it gas does nothing, car completely conks out. Battery dead again.
Tow to Merc dealer.
They replaced something called Voltage Separation Relay (was a fault in it), which regulates volts going from alternator to battery. Probably didn't need a new alternator after all.
Now all is ok.
Perhaps have that checked out?

04-08-2006, 02:18 AM
it sounds like you both were ripped off. the starter did not have to be replaced. the fuel trim problem is you mass air flow sensor, however, it should not cause your stalling problem. if it is the slk320 it sounds like it is your crankshaft sensor. when they are going bad they will create an open cricuit when they get hot. when they cool down the circuit closes and the car will start. both problems are very common and in this case if you both would have went to the dealer first it would have saved you some money.

if you have a slk230 I would also check the oil level. if it was over filled it could cause oil to get blowen into the intake and cause the mass air flow sensor to fail.

08-29-2006, 12:42 AM
I am the owner of an 2000 SLK and am experiencing the same problems as
dwy (SLK stalling etc). Unfortunately I have taken it to 4 different mechanics and none of them was able to figure out what the problem is. Hopefully dwy has fixed his problem; I believe he is no longer a user of this group. If anyone has exchanged any e-mails with him on this issue and knows whether he had fixed his problem I would be grateful to hear it.


09-07-2006, 06:30 PM
Crank sensor would make sense, if you had the car just stopped and there was no fuel trim codes. I am much more likely to beleive that the mass air flow has gone queer. IF it is not functioning correctly, that could be fucking up the mix.
Lately, I have noticed that a lot of the Bosch M.A.F.s seem to be going bad. Most of them were on volkswagen, but this could happen to the Benz.
On another note, I wonder how these machanics were diagnosing this condition. Did you lose spark? Fuel delivery? Did anyone check fuel pressure and spark, while trying to replicate the issue?
There have been intelligent things said by all who have posted, but the professionals that were mentioned did not seem to act as such.

01-03-2007, 01:27 PM
I have a 2000 SLK230 and have the same exact problem. I took it to a MB dealer and they could not figure out what the problem was. I was driving down the highway and loss all power. The car completely shut down. Here is my conclusion....I has to be the security system sending a message to the computer to shut down all power. When the car shuts off, the key has to be removed and the security unlock has to be pressed. This will give the computer in the car the ok message and the car will start again. It's a major glitch in the system that I feel "us" the SLK owners shouldn't have to deal with. We all need to come up with an idea for MB to recall this problem. It's a safety issue.

01-05-2007, 01:05 PM
I am going to file a formal complaint with the government. At this point I refuse to pay a dealer any amount of money to fix the problem. Maybe if all of us get together and file complaints we might get the ball rolling for a recall.
Here is the website: (
go to consumer compalints

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