BMW Key Fob Dead? Remote Start & Lock System Troubleshooting

Hey there! I've had some experience working on cars. I dealt with a similar issue on my 2001 BMW 5 series last year. The symptoms were exactly like yours, remote stopped working and had trouble with the ignition system. Turned out it was a faulty connection in the antenna wiring harness. Took it to my regular workshop and they diagnosed it pretty quickly. They found a loose cable connection near the antenna module. The whole repair, including diagnostic and fixing the connection, cost me around 95 Euro. Car's been working perfectly since then. Just to help better, could you share: Which engine variant you have? Are you getting any specific error codes? Does the key fob have a fresh battery? These details would help me understand if you're dealing with the same issue I had.

Thanks for the detailed reply! Mine's got the gasoline engine and I recently replaced the key fob battery, but still no luck. My mileage is at 115979 KM and had the last service about 4 months ago. Getting the error code P0513, which points to an immobilizer issue. Started happening suddenly last week. Good to know your fix was relatively simple and affordable, gives me hope it's just a wiring problem rather than something more serious. Might take it to the shop this week to check the antenna connections like you mentioned.

Hey again! Thanks for providing those extra details. I really see the similarities with what I faced now. That P0513 code is exactly what I got with my 5 series too! When you mentioned it started suddenly, it's almost like déjà vu, mine did the same thing. Just stopped working properly out of the blue. Quick question, before you take it to the shop, have you noticed if the issues get worse when it's damp or after rain? In my case, this was actually a telling sign. The loose connection I mentioned earlier was letting in a bit of moisture, which made the problem more noticeable in wet weather. The fact that you've already changed the key fob battery is good, rules out the simple stuff. Based on my experience, I'd put money on it being that antenna connection issue. The immobilizer error usually pops up when there's a communication problem between the key and the car, which fits with the antenna theory. Just a heads up, when my mechanic fixed it, they also checked the entire wiring harness while they were at it. Might be worth asking them to do the same for yours, just to prevent any future issues. The whole job shouldn't take more than a couple of hours. Let me know how it goes at the shop. Really curious if it turns out to be the same issue!

Thanks so much for the follow-up! You know what, now that you mention it, I have noticed it acting up more when it's been rainy. Didn't make the connection before, but that makes total sense about the moisture getting in. Really appreciate you sharing those details about your experience, it's super helpful. I've booked it in at the shop for tomorrow morning. I'll definitely ask them to check the whole wiring harness like you suggested. Having dealt with BMW electrical issues before, better to be thorough than have to go back again. Will definitely keep you posted on what they find. Thanks again for all your help, really eased my mind about this whole situation!