atraudes

Every once in a while, my fob stops working completely. After driving, I'll get out of the car, hit the lock or tailgate button on the fob, and nothing happens. Unlock, lock, tailgate, all are completely inoperative. I figured out that the fix is to put the key in the slot and turn it to the On position, then remove it and try again. Fortunately this has never happened while trying to unlock the car.

I've already tried replacing the battery (wasn't getting a low battery notification). This behavior happens very randomly and only once in a while: it could go months and never happen, it could happen multiple times in a day. I've never had a problem starting the car except when I leave the fob in the ignition for more than a minute or two, though taking it back out and trying again always works. I don't have a second remote to test with.

Anyone run into this sort of thing, or have any ideas on things to check? I'm due for a trip to the dealership at some point, so if I don't find a solution, this will get added to the checklist.

machinemanjr

Sort of similar occurrence happens to me: sometimes the keyless go functionality doesn't work. No response for lock or unlock. Hitting the button always works. I just assumed it was a random electrical gremlin.

Have you attempted to change the fob battery?

KEY08

Firstly, is your car keyless go? You don't say. If not, I suspect your key is beginning to fail on you.

atraudes

Whoops, sorry, I had it in mind but it got left on the cutting room floor! I do not have keyless go, no. It failing was what I was afraid of. Given that it's my only key, I guess I need to make that appointment sooner than later.

Yes, I changed the battery on the fob already. I figured the battery was causing the glitchy behavior, but it's happened a few times since.

KEY08

Lots of people have one key and I don't know how they can travel out of town with just that one key. Posters have come on here looking for answers to help them get going when they lose the one and only key they have. That is nuts.
I know that a key is not cheap, but it beats ruining a vacation. Shop around with dealers in your area for a new key. They need to be ordered directly by your dealer and there is no short cut.

atraudes

I'm completely with you. It makes me paranoid to only have one key, but lately other things in life have taken priority financially so I've been putting it off. I suppose the time has come!

I just called around and one dealer near me gave me a price of $360. The other dealer nearby wanted that plus $200 labor $360 is about what I paid for a new key for my '04 Volvo, so fortunately that sticker shock isn't anything new.

Sunnyslope48

Certainly your key could intermittently be bad, but so could the receiver of the key signal, or the circuit for the receiver. Intermittent problems are the pitts!

cetialpha5

Yes, EIS problems used to be pretty common in the earlier models. Search for it. Usually the way to diagnose it is with a second key. If they both act that way, it's EIS, if it's just one key, then it's the key. With just one key, they can't really tell although I suppose they could try scanning it and see if there are any error codes but even if they don't find any, that might not mean it's fine.

As for only having one key, add it to a bunch of other keys and put one of those Tile key finders on it. Also if you call around to a bunch of dealers in your area, you could find a lower price and then you could call your local dealer and tell them that a further dealer has it at a lower price and see if they will price match. Sometimes they also have service coupons you can use.

atraudes

Yikes, good point. Thanks for the heads up about EIS.

I think at this point I need a second key anyway, so I'll do that and see if the behavior persists.

Thanks for the input everyone! I'll post updates as I get them.

KEY08

I think that is the right approach and hopefully that will eliminate expensive MB diagnosis time for a simple fix.

Darel

The quickest and easiest thing to try, before working on the car, is open up the back of the fob and take out the battery. You will see there is a tiny metal prong that contacts (or is supposed to contact) the EDGE of the battery. Try bending this outward carefully to make better contact with the battery.

I have a spare key inside my dash that works with the Mid-City Engineering remote starter. When the weather got cold last fall the remote start wasn't working. Found that little prong on the spare key wasn't making contact anymore. Bent it out a little and all was well.

atraudes

Probably relevant update: on the way home from the dealership where I ordered a second key, the car started putting itself into park. Because, you know, life's a stinker like that. Oh well, at least I'll have two keys now. The second one should show up early this week.

https://mbworld.org/forums/e-class-w...ml#post7970727

KEY08

Ok, well you may have the EIS issue after all. Not sure what the repair cost is on that, but good luck!

B34chBum

Atraudes said his new key is ordered... Hasn't been stranded by new key (yet).

I had just about convinced myself to dig the EIS out and fix the (assumed) issue with the solder joints inside... Then I replaced the battery in my (only) key, and was left dead in the driveway.
Since getting a new key, I haven't had any issue starting, so likely no EIS issue (will see when the weather turns hot again, that issue seems to manifest when the under-dash area is warmed up and humid).
For me, after all this, I still have only one known-good key, the New one.

Good you have one on the way, OP!

atraudes

The old fob is the one common link between the two issues, so fingers crossed. I'm planning on picking it up this Friday.

LILBENZ230

How much is the new fob costing you from the dealer?

atraudes

$400 after tax. I did like cetialpha5 recommended and called around to a few dealers to try to find a lower price, but that was the best the local ones could do.