Lost Key

[GianAgius]

Hey guys. So my dad lost his car key and went to use his spare key. He told me that the car unlocked using the key hole as the buttons on the remote weren't working. He went to try start it and he was telling me that it didn't start. Could it be the battery is dead and the immobiliser isn't deactivating?

will changing The battery of the remote let the car start?

[bluptgm3]

Which model car are we talking?


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[TxDarth]

Key battery has nothing to do with the car starting - only controls the remote functions. That car battery might be dead tho....

[Grady in Texas]

Doesn't the key need to have an RFID anti-theft chip? Maybe the plastic ones do.

[psjr]

Key battery has nothing to do with the car starting - only controls the remote functions. That car battery might be dead tho....

+1 to everything TxDarth said ....

[GianAgius]

But the car started perfectly fine with the other key (the lost key) he had used it that morning so I dont think the car battery is dead

[bluptgm3]

What does the spare key look like? What are the materials it is made of?


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[Qsilver7]

All BMW keys have an EWS transponder chip in them...remote keys as well as the multiple non remote keys (since Jan/1995)...unless a previous owner pried a key open and harvested the chip. The transponder is inside each key (see gray area in pic below)...but the new style (diamond shaped) remote key's transponder is soldered to the key's internal IC board...which is different than all the other keys & old style remote key.

{old style remote key's EWS chip}




{new style remote key's EWS chip}

[GianAgius]

Ah Christ, that's the problem. The key doesn't have the EWS chip in it... don't know where it went.. could explain why the car isn't starting.. The key is the older design btw so its not soldered to the board, any idea what I can do? buy another key?

[Qsilver7]

Ah Christ, that's the problem. The key doesn't have the EWS chip in it... don't know where it went.. could explain why the car isn't starting.. The key is the older design btw so its not soldered to the board, any idea what I can do? buy another key?

If the EWS chip is missing from the remote key...then that is definitely why the key is not starting the car.

If you can't find that little black chip...you can't buy it separately. The best thing to do in this case is to go to your local BMW dealership and order a valet (service) key...then harvest the chip from it and insert it into the remote.

The plastic valet/service key is the least expensive key (in the USA it usually cost between $45-$75)....see the key on the right in pic below:

[GianAgius]

Lovely... my dealer tends to charge ludicrous amounts of money for parts, just a reference the normal key costs around €350 from them, cut and programmed so I don't know if that's a good price, but it is steep. Thanks for the help I'll have to go to the dealership and ask them how much it would cost for the plastic key.

[Qsilver7]

Here's another pic that shows how the EWS transponder chip is placed inside a BMW plastic valet key...and how it can be harvested and placed inside the old style remote key if a new chip is needed. The hardest part will be trying to figure out how to open the plastic key to get to the chip.

[psjr]

If you're only missing the chip, you could try finding a locksmith who can make them. You need to remove the EWS from the car and give it to them to program the new chip in.