When I lock the door, after about 20 minutes it can not be unlocked with the key fob. I replaced the battery, and when that didn't work, then the fob. When I unlock the car with the key after the 20 minutes, the alarm sounds. What should I look at next?

 

The key part is normal. You'd need to put the key in the ignition within the allowed time.

The rest isn't. Consult workshop manual? Free download.

 

The alarm sounds when you open the door, it is immediate. Then there must be a way to reset the the time?

 

I do hope I'm wrong, JCJ, but I have a nasty whiff of a serious misunderstanding here . . .

On a 2008 S-Type . . . please describe precisely how you "changed the fob". Certainly my 2007 S-Type (most '08s were made in '07 also), and all others of the post-facelift era I have seen, use 3 keysets of combined key, transponder and remote (1 being green for valet). Unless you have used the dealers to re-program a new set, your "new fob" is not registered to your car's PATS, thus triggering an immediate intrusion alarm.

Suggest you use one of the alternate, original key+remotes and advise . . . but perhaps you have and this is what you mean by "changing fobs" . . . in which case, ignore the preceding while I start breathing again. Either way, please clarify for us.

Best wishes,

Ken

 

I am the 3rd owner of this car. The lock didn't work properly when I bought it, but I didn't know (it was unlocked when I got there). It is not the key or the fob, both work properly all day long, just as long as they are used when in the 20 minute time frame. Also it was made at an authorized shop.

It seems to be an issue, where a battery backup or capacitor is drained after this approximately 20 minutes and the fob no longer opens the door and using the key sets the alarm off immediately upon opening the door. I have read the manual and just can't seem to locate a part to suspect.

 

I can't escape the feeling this would go so much smoother if you just answered Ken's question directly.....

Summary: JCJ is the 3rd Owner. The car has always exhibited this behavior since day-one of 3rd ownership. JCJ has more than one FOB. At least one of said FOB's were not delivered with the car to the 1st owner. (Not an original FOB) The discrepant behavior is present when using either of at-least two FOB's.

Fair summary? or not?

If so, How many keys do you own? If >1 (and the only PROPER answer is Yes! if not...get yourself another key before you get caught out with none!) Have you tried more than one key?
What is the genesis of each FOB? (Original or "authorized shop")

Just a hunch, but it sounds like Key/FOB/PATS have not been properly introduced to one another.

 

As Zane hinted above, when the keys are programmed they must all be present for the programming process. You cannot just purchase a new key and expect to add it to your collection unless you do the reprogramming process again with all old and new keys present....

 

I have 3 keys, the original I was given when I bought the car. The one they cut, as a valet key, and I carry in my purse, just in case I lock the key in the car, and the new key that I had made. The old key is my husbands copy. All the keys and fobs were programmed together and work properly.