Remote keyless entry problems

December 17, 2006 7:15 AM

Remote keyless entry problem.

OK, so I have a BMW 3 series, 2003 and recently the remote locking has been acting up. Recently both keys failed. I can get in the car and drive OK, but it's a pain. Been to the dealer and had the keys re-initialised, but nevertheless, one key works and the other still doesn't. Have WD40'd the locks and the bonnet/hood sensor, checked the fuses, etc. so not that. In fact, as it is clearly an intermittent problem it is likely the keys not the car. Keys have an integral battery, charged by the ignition. It isn't location based - eg happens anywhere.

Odd both should go at once. Was wondering a) anyone have any experiences to offer b) if it is the keys the surely the electronics are pretty solid in the moulded fob? There is room at the edge of the buttons for gunk to get in there though - would it harm the electronics to flood them with WD40?

posted by A189Nut to travel & transportation (8 comments total)

I see varying stuff about this. Normally, remote key fobs just have a watch battery inside. The advice is "change the battery". It would not be surprising for two batteries in use since 2003 to both run out of juice at about the same time.

There seems to be some disagreement on the Internets about whether BMW has made the battery in their remote key fobs rechargeable. (I have never heard of such a thing, and it seems like it would increase the size and complexity of the key fobs for no very good reason, but it's not outside the realm of possibility to charge the key fobs via induction.) If it is rechargeable, the advice then might be "drive places using the key fob inserted into the ignition to recharge the remote battery".

Follow one or both of these pieces of advice. WD40 won't help anything.
posted by jellicle at 7:44 AM on December 17, 2006

The key has an integral battery - can't be replaced. It is recharged by an induction coil in the steering column. I have tried re-charging it. WD won't help, but also won't harm?
posted by A189Nut at 7:52 AM on December 17, 2006

WD40 is horrible for locks. It attracts dust and the resulting goo will really gum up the works. Use graphite powder instead.
posted by buggzzee23 at 9:11 AM on December 17, 2006

Graphite powder
posted by buggzzee23 at 9:14 AM on December 17, 2006

Ah, why is all the good stuff in America?
posted by A189Nut at 10:04 AM on December 17, 2006

I recommend reading a few of the E46 forums. You'll have to sift through a lot of junk, but you might find what you need. If not, join and ask. The obsessive fan base for this car, especially here in the States, is such that you'll get a good answer.

From my own experience, a 2000, both of my keys are fine -- even the one I didn't use for four months unlocked the car remotely the other day. Please, don't spray WD on your key.

Just guessing, it's likely that you need a new key. This should be covered under warranty, I'd imagine. But check the forums.
posted by luckypozzo at 11:07 AM on December 17, 2006

I'm confused - the key has an internal, rechargable battery... but don't keys that have batteries have RFID for security only? Shouldn't the key FOB - the item that does the unlocking, have a separate, watch-style battery?
posted by IndigoRain at 4:21 PM on December 17, 2006

Rechargeable batteries have a finite lifespan too, and they're very affected by temperature. Were both keys recently frozen, or close?
posted by Myself at 5:07 PM on December 17, 2006