2000 S500 Won't Start
 

2000 S500 Won't Start

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I've been doing some research on this forum, it seems that the most common answer to my problem is the CPS; however, I am not sure if this applies to my situation.

2 days ago when I was trying to start my 2000 S500 in the morning (the engine was cold), it cranked, but didn't start. I tried holding the key at the ignition position, the car would keep cranking, but just won't start. I tried again at noon, and it started with no problem. I took a short drive, parked, and started again without any problem.

I drove again this morning for about 50 miles, and left it there for 6 hours, now it won't start again. The symptoms are the same. The car cranks but just won't start.

After reading through the forum, I learnt that if the problem is caused by CPS, the car usually stops when the engine is warm. But in my case, it seems to happen when the engine is cold or not that warm.

Any suggestions? Thanks in advance!!

hi - this actually does sound like the CPS...but the problem is at its early stages..but as time goes it will get very annoying and worst still...unable to start in warm and cold.... solution: just get a replacement CPS.

yes please replace that CPS NOW!!! It will continue and get worse. Nothing is more embarrassing than being stalled out at a busy intersection in Mercedes Benz, well maybe pushing a Mercedes Benz out of the intersection...lol.
This place www.autohausaz.com has the part for considerably cheaper than anywhere else, either you can install it yourself or have a Euro mechanic do it

Yeah, replace it. It will get worse and get embarrassing.

Thanks guys, I've just ordered the part. I was told that this could also be caused by the fuel pump?

hi - to check whether the fuel pump is working......you can listern to the 'whirrling' sound....just before you crank the engine.....the fuel pump will be activated before the crank.....if there is a 'whirrling' sound...this means the fuel pump is fine....

But i suspect it is the CPS which is giving you the problem.....

Thank you so much for the input!

i had the same exact problem and it was the cps, mine would not start in the morning after long park, it would keep cranking and sound like its about to start but no it wouldnt, then i would sit in it for about 5-10 minutes and try again and it would work.

it mostly happened when i left the car parked for a while and then tried to start it.

anyway you can get the Crank sensor for about $50 i think from auto zone then a mechanic shouldnt charge you much for installation, so its not that expensive of a repair

LOL, I was so freakin embarrassed, and virtually NO-ONE would help. I guess just something about a guy in a suit sitting in a stalled Mercedes that says LAWYER on the license plate turns people away from helping lol

hi - A few years ago, i had a 'conservation' with a mercedes stealership and he told me that the CPS is a sealed unit, where there should be no rust. But upon opening and examining the CPS I found that the CPS unit is rusted inside.

This means we know better than the mercedes stealership.

Unlike the OP, in the mornings (65-75 degree outside temp) the key (brand new one and old one) will turn to position 3, and all electronics will work, but it will not even turn over. Sometimes after several attempts it may decide to turn over and fire up. other times, we wait until the temp outside is warmer and it fires right up. This morning it would not start all, but after sitting for another 6 hours, I went out when it was 91 degrees outside and it fired up without issue several times.

Still a CPS issue or something else? :nix:

Mine is a 2004 S500 if that info is needed.

No that's not a cps. A bad cps would start and work in the morning when it's cold , but not work when the car is warmed up

Your problem might be the ignition switch

Thanks. Something tells me that might not be a DIY item.

The ignition switch can be repaired . That's the cheapest way

It can be replaced with a new part at Mercedes but it's $$$$

If you get a used one you need to change all 4 of the anti theft parts (shifter key ignition switch and ecu) by using parts that are a matched set from the same donor car, because they are programmed to only work together