2003 BMW 5 Series
Key Replacement - Save vs Dealer in Ventura County

2003 BMW 5 Series Remote Head Key Replacement - Fast, Affordable & Professional

I got a call from a guy parked near the marina at Channel Islands Harbor in Oxnard.

He had driven down from his place to meet his boat, turned the car off, and when he came back the remote head key would not unlock the doors. It would start the car if he got in manually, but the remote functions were completely dead. He had already tried the lock and unlock buttons standing right next to the door. Nothing.

He had owned the car for a few years and never replaced the key battery. That was the first thing I asked on the phone.

When I got there, the fob looked fine from the outside, no cracks, no obvious damage. I opened it up and the CR2032 was reading low on my tester. Not dead, just low enough that the remote circuit was starving while the transponder side -- which draws less power -- was still getting just enough to let the car start. That is a common split on these E39 keys and it confuses owners every time.

Fresh CR2032, contacts wiped, fob closed back up. Remote unlocked the car from across the parking lot on the first press.

I still ran the full test before I packed up. Every button, remote range walking back toward the water, three starts. He watched the whole thing and mentioned the dealer had told him over the phone that the fob probably needed to be reprogrammed and quoted him accordingly. A battery and a contact cleaning was all it took, and that is exactly why I test before I assume.

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