I have searched and would like other opinions. I have an 04, stock with original battery. Today I locked the car with keyfob went in to grocery store came out ~30mins later and keyfob would not unlock the car. Had to use the key to get in, alarm went off. I started it with the key and all was fine. When I got home I tried the other keyfob and it doesn't work either. Both lights light up on both keyfobs. The lock/unlock works fine with interior switch and hard key. I checked fuses and nothing seems out of sorts. I did read where others say the car is funny about old batteries. However I also read where there has been water issues in the trunk or maybe the SKREEM? module isn't getting the signal. Not really up for tearing into the back to look for water or fool with the module in the dash, esp when the locks seem to be working fine. Also car starts fine all other electronics work, lights, horn, spoiler, etc. Was planning to just get a new battery tomorrow unless anyone has a better suggestions for me. Thanks.

 

Welcome to the forum!

Good to start with a new battery.

You already hit on some of the known causes.

Lets hope the new battery does it.

 

I'd first try new batteries in the FOB's because they are dirt cheap. You can get a package of 10 batteries on eBay for under $6. They are CR2025 batteries, and each FOB requires two. The Owner's Manual tells you how to replace them - it's super easy, just pry open the little door on the FOB.

10 pc SONY CR2025 CR 2025 Lithium 3 Volt 3 V. Battery - eBay (item 300390740093 end time Apr-25-10 22:57:03 PDT)

If that doesn't help I'd replace the main battery in the car. Being it is still the original battery it's overdue for replacement anyway.

 

Thanks. I was thinking that I'm pushing my luck on the main battery anyway. I might have some of the coin cells at work...will find out tomorrow. I have been a visitor to this forum for over a year now. I had the tranny sensor problem, cost me $900 to get fixed last Fall. out of warranty. Chrysler dealership is a waste of time. Love to sell tires and oil changes but tell you to go away when anything of substance happens to the car, excuse is they have no XF tech. I get compliments on the car constantly...just wish I could have gotten a white one instead of black. Can't be picky when you buy used and get a great deal!

 

Thanks for the link and info.
I have an 04 I got 3 years ago and never changed my remote FOB batteries.
Better safe than sorry right.

 

how would a new car battery help solve this problem

 

Some of the posts I've read on here and mercedes forum say that the electronics are finnicky if the car's main battery is providing low voltage. Guess that might now allow the remote to activate the locks if it weren't getting enough voltage when the car is off. I'll let everyone know what I find.

 

maybe I need to replace my battery then I'll find out when my new key gets here

 

I've been having a similar problem. I have 3 keys and they all don't register a lock/unlock until about 2-5 feet away. This just now started happening about a week ago. I just put in a new car battery and the key fob batteries aren't that old.

I did have to pick up the new car battery from wal-mart when I was in a jam, so does anyone think that the quality of this battery may have an affect? It seems to be getting weaker even after just 2 months of use. Suggestions?

 

Okay so I bought two new Energizer Li coin cells from Target $5.99. Installed them into the key fob and nothing. So I decided to do the old disconnect the battery for 10mins. Well for whatever reason the alarm started barking about 30 seconds into disconnecting the batt. Hooked the batt back up key in ignition to get the alarm off. Reset the BAS/ESP and voila the key fob started working, both of them. So that's my experience if it happens again I will go for the battery. May order one just to be safe given the age of it.

 

I lost key fob functionality again over the weekend. So I went on the try to find a Crossfire battery quest. 1st stop Costco, don't carry it, 2nd stop WalMart, don't carry it. 3rd stop NAPA, they had an exact drop in, 2 in stock. Looked just like the Varta except it has a black case. $110 after core return. Installed it in the driveway in under 15mins. So far so good but let's see what happens in a week.

 

Thanks for the Battery key FOB info, just ordered a set from E-Bay. One of my remotes has just stopped working, this SHOULD resolve the problem. (Hopefully)

 

Ditto on the post about key fob batteries. Just ordered a pack. Thanks.

 

I am still having problems with my Remote. I Put in new batteries, now the Remote will lock the car but will not open it. As I have tried my spare Remote, which works perfectly, I have put it down to me needing to get a new Remote.

 

Terry I would say your analysis is correct. Sorry the cheap fix did not work.

 

TerryR, the fob may just need to be re-programmed. Somewhere on the forum are the simple instructions for programming a new key fob. Do a search or maybe someone with better re-call than I can provide them. Or, the "unlock" button may just be broken. :-(

 

resynchronize your key after replacing battery in fob ? saw this some where ! push unlock 2x on fob then put key in to ignition turn to 2nd pos within 30 secs should do it ????

 

Three years late with that hint, LOL.

 

Whats the old saying better late than never ?????????

 

or was it better never late said the BOSS !!!!!!!!!!!!!