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Wondering if anyone has dealt with this. The car decided to stop recognizing my key fobs intermittently. Started one afternoon, and was completely dead the next day.
My 2nd key also worked intermittently before everything stopped working it's not the fobs. Must be the EIS (electronic ignition switch) or the ESL (electronic steering lock).
Called the dealer, and was told the EIS is a theft related part (TRP), which means that a) the car has to be towed in, and b) they have to do the work. Makes sense, as the modules are tied to the VIN and aren't fungible without extra coding. However, for TRP, proof of ownership (such as insurance) isn't sufficient.
1) anyone know how to definitely identify if it's an EIS failure as opposed to ESL? My logical guess is EIS, but would like to hear another opinion.
2) Anyone have experience getting the EIS or ESL repaired/replaced by a 3rd party? I'm probably going to go this route as the dealership price is absolutely insane. If so, any specific businesses you can recommend? Apparently some places can either a) bench repair the device, or b) clone it into a 2nd (donor) module.
At the end of the day, I just want a working car.
Last edited by slammer111; Jun 25, 2025 at 02:43 AM.
intermittently can be a hint that you deal with cold solder points and the change is good to repair it yourself. It is a pain to get it out but easy to open. You have to lay on your back in the footwell and reach with your arm behind the dash.
With the steering wheel in low position you have enough room to get it out.
So after sending my EIS to a professional shop, apparently my stock one is kaput. Mechanical issue with the barrel mechanism. Electronics are fine. They just cloned the data into a new EIS and sent back both units.
Car starts. Both keys are recognized. Doors remote lock and unlock.
Everything works except my car now throws some light sensor error. I know this error can be caused by a bad battery or voltage regulator, but a) the battery voltage looks fine, and b) this problem wasn't there before I removed the EIS.
Light sensor - drive to workshop!
I talked to the guys who did the reprogramming and they said it's most likely an incorrectly coded/configured option, and that it should be a very easy fix for someone who knows what they're doing. Probably something as simple as unchecking a flag. Unfortunately they're not local, so I can't just get them to look at it.
Can anyone with access to Star/DAS tell me the menu path for getting to the light sensor menus, or at least point me in the right direction? Guessing that the car is expecting an input from a (non existent) 2nd light sensor. Thanks in advance.
Last edited by slammer111; Jul 15, 2025 at 10:23 PM.
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
Light sensor DRIVE TO WORKSHOP?
Like it's soooo serious. You must drive to the werkstat now!
Yeah, so they can milk you for a grand.
Does the car operate ok?
It's an anoyance to have to see that everytime, but maybe no more so than NO PHONE!
I did see some menu's in my new Lauch Elite 2.0 Merc scanner for calibrating the light sensor?
I wonder if it could be as simple as that?
BTW- what was the shop? Sounds like a good resource.
Last edited by C230 Sport Coup; Jul 16, 2025 at 02:06 AM.
Talked to the shop and they sent a 2nd replacement under warranty. The technician double checked the programming this time, and everything works. Had to do the "hot swap" (between 1st and 2nd replacements) while in USA which was a bit of a risk in terms of getting stranded, but the 2nd replacement worked right out of the box. They also included a shipping label so I could mail the 1st replacement back.
All is well. Back on the road.
Looks like all of the shops that can program/clone W203 EIS modules are located in USA. I was unable to find one in Canada willing to take on the job.
Originally Posted by C230 Sport Coup
BTW- what was the shop? Sounds like a good resource.
The shop I used was The ECU Pro based out of Wellsboro, PA. Very professional. Great support and fast shipping (within USA). They definitely know their stuff. I am a happy customer. FYI they also provide services for other modules (ECU etc.), as well as other German makes. Mail in whatever module and they service it and mail it back out. Pretty good business model actually. There is definitely a need for this service out there.
Last edited by slammer111; Aug 6, 2025 at 12:13 AM.
Thanks for posting this information. I don’t have this problem, but I am planning to keep my C230 for as long as it is visible and it seems like something is breaks at least once a year. I have used information from several of your posts to to repair my car. This may be information I need in the future.
Thanks for posting this information. I don’t have this problem, but I am planning to keep my C230 for as long as it is visible and it seems like something is breaks at least once a year. I have used information from several of your posts to to repair my car. This may be information I need in the future.
Tell me about it. I had 3 separate repair jobs this week alone (the EIS being one of them), and 4 for the year so far. Nothing critical broke last year though, so it's hit and miss.
My EIS died last year. This does happen. My alarm going off on it's own was one of the tell-tale symptoms that led to the diagnosis. $1500 later at the dealer and everything has been fine sense.
My EIS died last year. This does happen. My alarm going off on it's own was one of the tell-tale symptoms that led to the diagnosis. $1500 later at the dealer and everything has been fine sense.
Just curious, what was your mileage when your EIS failed, and which PN did the dealer install?
I successfully repaired the EIS by changing the voltage regulator on it and found broken solder points. It is worth to open it and take a look to it with a magnifying glass.
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Engine ignition switch (EIS) / electronic steering lock (ESL) failure
FYI they also provide services for other modules (ECU etc.), as well as other German makes. Mail in whatever module and they service it and mail it back out. Pretty good business model actually. There is definitely a need for this service out there.
