I searched the web could not find the answer accept to replace the part where the key goes in, forgot the name..

Anyway, I bought two brand new keys from the dealer. $600.00 total!
When I start the car it turns right on. But for a second than turns right off. Try again and does the same thing. Sometimes it does turn on and stays on but it's a 50/50 chance. This is the case for both brand new keys.

My old original key does not have this issue. It turns the car on each and every time and it stays on.

At first I thought it was the fuel pump going bad. But since the old key has no issues it can't be that.

Called dealer they said bring it in so we can find a way to get more money from you. Before I go in, have any of you guys had this problem or know of it? Any suggestions why this is happening?

Thanks for any input.

Just wondering if the new keys need some code pairing with the electronics. If so, probably you will be needing a connection and session on Star or something similar

I got a new key last Fall and had the same issue. It was getting pretty bad. My car then sat for a few months while it was in one state and I was in another and I just had it shipped over and it starts right up now. I'm not sure if that is because the weather has gotten better or if the system just adapted over time. I did install a battery tender jumper before I left the car to sit for a few months and did have to disconnect my battery for a few minutes during the install. I just had to reset my windows and sunroof and I'm wondering if resetting the electronics in the car made the new key work better. Might be worth trying.

I have read that the ignition switches can go bad on these cars but I didn't go far enough into my diagnosis to actually cost out a new part. Crossing my fingers that it is solved for now but I know exactly what you're talking about.

Hmmm , perhaps disconnecting the battery for a moment may solve the problem. Just need to reset the windows, but your TCU will also flush also

The dealer said the keys don't need code programming. I remember a few years back the same dealer said the car needs programming so the keys would work. They wanted to charge 100 bucks. Seems they dont know what they are talking about...

I'm going to try disconecting the battery and see what happens. Thanks guys!

K40 relay try replacing it.

I heard this cause this sort of startup symptom

For those not electric minded, where is the K40 relay and what's it's purpose?

Not as frequent as you but that happens to me every now and then, the dealer told me it's a problem with the new keys and the eis and they said another few thousand to replace the computer's would fix my problem. Seemed fishy to me

I disconnect the battery both positive and negative for like 15 minutes. So far I've started the car 15x and each time it has started right up. Hopefully it keeps up. Thanks drb.

Going to replace the K40 relay as pj suggested IF this problem comes back.

Car this morning still starting every time.

Didn't want to start a new thread. Does anyone know where the Ballast for the driver side located? Are there any other Ballast you guys recommend besides oem?

Thanks in advance.

Which ballast? Are you thinking of the Xenon headlights? If so you need to remove the front wheel and unscrew the wing lining. The ballast is behind on the chassis beam. Usually very dirty and corroded. Beware not to snap the holding screws. Apply plenty of WD40 or similar. The passenger side is the exact same operation.

Yes the xenon Ballast. So remove the DRIVER side wheel right? That's what I read online but it was for another Mercedes not the w202 so wanted to make sure before removing wheel and stuff.

Correct

BTW where did you find a ballast? New they cost an arm from the dealer and finding them on the net is also expensive. I did source new ones at a very cheap price. If you are interested I'll send you more info by PM

This doesn't apply to cars that are in good climate areas

top pic is a auxilary fan relay no?

I need one if anyone has a good spare

Yes please send me the info where to buy one. I have not looked for one yet. My xenon light stopped working but the bulb is brand new and it does work. I checked all the wires and all looks good. So has to be this Ballast. Fuse is good too. If you know where to buy the front glass for the light housing let me know too. Mine is cracked. I'm trying to restore this 98 c43...

You are right. Sorry didn't realise when I chose the photo

https://www.ebay.com/itm/2000-2002-M...-/253490742081

What do you guys think about this? Check link, it's for a audi tt and guy says it works on a w202 with xenon lights. But I would have to do this, according to the seller.

The connector that attached to the ballast is obviously compatible, the other side of the harness that attaches to the headlight needs to be swapped. You can go through the process of removing the pins, or cut and splice your connector onto the harness.

This one is more in line with what you are looking for. Looks similar to the ones I ordered in 2017: https://www.ebay.com/itm/AL-Audi-BMW...75.c100623.m-1

Will I need any different wire plug or anything else? Or is it plug n play?

Should be perfect plug and play, if the photo is the image of the real thing

Thanks Daniel sound great. I emailed the company they gave me a price of $155. 00 shipped. That's pretty good compared to oem used ones..

so did you figure out the no start problem?

It's been days and MANY starts and it has stayed on each and every time! All thanks to Daniel's advice to disconnect the battery. What I did is completely disconnected both positive and negative wires for like 15 minutes. I did this because I had to pull the battery out for something else I needed to do. So you may not need to do exactly like I did and wait 15 minutes long. But after doing this BOTH keys now work great.

located inside electrical box on the passenger side of the engine bay
http://www.peachparts.com/shopforum/...-one-pics.html

Example for demo purposes