Question 1

My key broke in the ignition. Can you get it out?

Accepted Answer

Yes. The 1999 5 Series has a physical ignition barrel, so a broken key blade is extractable on site. I pull the broken piece, decode the lock cylinder, and cut a replacement key to match. No tow required, no ignition replacement unless the barrel itself is damaged. Once the new key is cut, I also verify the transponder is in sync with the immobilizer before calling the job done, because a freshly cut blade that hasn't been confirmed against the security system is only half the job.

Question 2

What exactly is a remote head key and why does my 1999 BMW need to be programmed?

Accepted Answer

A remote head key combines the key blade, the transponder chip, and the remote fob buttons all in one unit. On your 1999 5 Series, the key carries a transponder that communicates with the vehicle's immobilizer every time you go to start the car. If that chip isn't recognized, the engine management system cuts off fuel or ignition and the car won't fire, even if the blade turns the cylinder perfectly.

The 3-button remote portion handles lock, unlock, and trunk release and needs to be synchronized separately from the transponder side. Both have to be correctly set up. A replacement key that's only been cut but not programmed will turn in the ignition and do nothing else. That's why I handle everything on site, transponder enrollment and remote sync, before I hand the key back.

Question 3

My BMW is showing a key-not-detected warning. What should I do first?

Accepted Answer

Start with the battery in the fob. CR2032, and they do go flat without much warning. A weak cell causes exactly this symptom: intermittent warnings, reduced remote range, or a complete dropout where the car acts like the key isn't there.

If a fresh battery doesn't clear it, hold the key directly against the ignition barrel. The antenna ring sitting around the barrel can pick up the transponder signal at close range even when the remote side is dead. If the car starts that way but not from normal position, you're dealing with a signal issue, not a lost programming issue. If it won't start either way, the key likely needs to be re-synced with the immobilizer, which is a shop tool job. I can do that on site.

Question 4

Can I buy a replacement fob online and program it myself?

Accepted Answer

Not on this one. The 1999 5 Series immobilizer system doesn't have a DIY button-sequence or ignition-cycle trick to enroll a new key. Pairing a new remote head key requires dealer-level or professional diagnostic equipment connected to the OBD port. If you've already bought a fob online, it may still be usable, but you'll need someone with the right tools to finish the job. Bring what you have and I'll tell you whether it's compatible before we go further.

Question 5

My 1999 5 Series cranks but immediately stalls after I start it. The key is the one that's always worked. What's going on?

Accepted Answer

That specific pattern, cranks and fires then cuts out immediately, is a classic sign that the immobilizer is interrupting the start after the initial ignition event. It doesn't mean the key is physically bad. It usually points to a communication breakdown between the transponder in the key and the security module, which can happen after a low-voltage event like a dead battery, a jump start, or even just an aging transponder that's starting to drop signal.

It can also follow a module swap somewhere in the car's history. If a prior owner replaced the instrument cluster or another control unit without properly re-matching the security components, this symptom can show up seemingly out of nowhere.

I diagnose this on site. If the key and module are still paired but have a stored fault, a reset usually clears it. If synchronization has actually been lost, re-enrollment through the OBD port gets it sorted. Either way, a crank-and-stall on a car that was running before is usually recoverable without replacing anything.

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1999 BMW 5 SeriesKey Replacement - Save vs Dealer in San Diego

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1999 BMW 5 SeriesKey Options