The remote key fob won't open the doors by pressing any keys on it. I can, however, lock and unlock all of the doors by turning the integrated key inside the driver's door. So the central locking system works fine. It's just the remote that doesn't work.

The key fob seems to be working - accordingly to some specialist who tested it with his gauge. The battery replacement also didn't help. I've disassembled the diversity module and it looks as it was new. It does not look as if water got into it or anything - it was just dusty.

The radio reception is flawless. So I have idea where to go next. Is there a way to test the diversity module somehow? I don't want to blindly replace it and face the same issue.

The BMW in subject is E91 2006, 320d.

2 Answers 2


I suspect the key has lost its "sync" to the diversity module. You can take the module apart (like you already have), and scrub it clean with high strength isopropyl, or even good vodka (but I feel this a waste.)

I know you said it was only dusty, but a good clean won't hurt anything. Beyond that, it's a dealer-only effort. This is coded RFID Bavarian voodoo magic beyond my comprehension. Fob battery or dirty module. Fixed. No? Dealertime and wallet weight loss. Sorry I don't have an inexpensive answer.

Just curious, have you put the fob directly on the rear glass to see if that makes a difference?

  • Yes, I did try to put the fob directly on the rear glass, no difference. The diversity module's case was dusty, not the circuit board itself. It was clean as it was new... :) I wonder - is there a way to verify whether the diversity module is fine? Some voltage measuring, etc? Every mechanic says that I have to replace the module but what if the wiring is messed up? Do you know maybe, beyond powering wires, what signals should be expected on other ones attached to the module?
    – Cleankod
    Aug 10, 2016 at 8:49

check the wiring in the far right flexible house that goes from tail gate into car body, you'll likely find a broken wire, very common issue on e91. you will have to cut the rubber boot to expose the wires. its caused by the repeated bending of the wiring loom when opening/closing boot. check this 1st before unnecessarily changing the diversity amplifier.

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