[Smallblock454]

I have a customers' 9x6 with a M534 alarm ecu water damage. European car, so M534 and 433.92 MHz system.

Car was fitted with a 996.618.260.00. I received a 996.618.262.02 from Porsche as a replacement.

Everything has been drained and dried. Wiring harness has been checked. Connections have been checked and cleaned. Antenna has been checked. Everything seems fine so far.

Programmed the new unit and everything works fine for about 2 days. Then suddenly the keyfob where only recognized from when you put them directly beside the drivers window,

No error messages / DTCs.

Measured the keyfob signal strength. Perfect.

Measured antenna and tested against ground, no abnormalities. Replaced antenna with new original antenna. Problem still exists (this M534 has an extra antenna connector).

Installed M534 with the reception problem in another car - same phenomenon - handheld transmitter is only recognized directly on the windscreen / driver side window.

Put the M534 from the other car in the car that had the water damage. Everything works as expected. Key fobs are recognized from 5 to 6 meters.

Ordered another M534 from Porsche, programmed it to the car. Now everything works fine, but…

now 2 days later the key fobs are again only recognized, when you put them directly in front of the windscreen / driver's side window. Aaaargh! It's so bad that they aren't recognized when you stand in front of the trunk or the passenger's side door.

I can rule out any interference problems.

I'm running out of ideas.

Any ideas what can cause the M534 receiver to "die" within approx. 2 days?

Anyone had a similar experience?

Thanks in advance…