BMW key fob | Auto Lab Libertyville

How a Dead Battery in the Key Fob Wreaked Havoc for a BMW 4-Series Owner

We recently had a client come in—on bicycle—because her BMW 4-series convertible wouldn’t start.

She was parked in a lot in Libertyville, and when she first came back to the car to find it wouldn’t start, she called a tow truck. In order to load a vehicle onto a tow truck, you need to put the transmission in neutral so the tires and wheels can roll freely. In this case, the BMW uses an all-electronic start, making it impossible to shift the car into neutral when the engine isn’t running.

The engineers at BMW saw the potential issue with this and created a solution—sort of. When the client called BMW roadside assistance, she was told that she/the tow truck driver could release the gear shift by inserting a 5 mm Allen wrench into an access panel beneath the car. Well, the car only sits a few inches off the ground. There wasn’t enough clearance for anyone to get under the car. The tow truck driver decided he couldn’t do anything and left, but our client was still stranded.

How Auto Lab Got Involved

At this point, the car owner obtained a bike (we’re not sure from where) and pedaled on over to Auto Lab. I grabbed the jumper pack to jump start her battery, and we headed back to her car. We tried to jump start the car, but still had no power.

That’s when I noticed something: When I pulled on the door handle, the window would move a little bit. This told me the car wasn’t actually dead. The car did have power. Something else was wrong.

At this point, I determined that I couldn’t do anything else unless we got the car back to our shop. I called BMW myself and explained that we needed to jump start the car. The “ever-helpful” agent on the other end of the phone gave us the “I already told her what to do” line and then said we should call BMW service and have the car towed to them.

You can imagine that wasn’t my first choice. Then I had another idea: What if the key fob is dead, and the car doesn’t know the remote is in the car?

A Simple, Cheap Solution to the Car Not Starting

We went back to the shop and put a new battery in the key fob. The client went back to her car and guess what? It started right up.

The whole problem had been caused by a dead battery in the key fob. Because of the dead battery, the car couldn’t recognize that the key or its transmitter were nearby. It wouldn’t lock or unlock the doors, start the car or do anything else. And the only clue we had was the window that moved ever so slightly.

The moral of the story: Most of today’s cars need the transmitter from the key fob in order to start. If you suspect your key fob battery is fading, don’t delay in having it replaced. Procrastinating could leave you stranded. And if you have a case where the car won’t unlock or won’t start without warning, ask yourself if the key fob battery might be the culprit.

In this case, the client only paid $25 for service and was on her way.

Here’s to your car starting every time!
Auto Lab Owner & Founder

Posted in Auto Repair, Diagnostics.