My own fault. 'I parked my '05 E55 in the driveway in preparation to change the fuel pumps/filter. Previously, I pulled the cover off of the SAM/ECU box while troubleshooting the stalling problem with the intent to replace them when I completed the fuel pump/filter install. I was going to replace the parts Saturday but ended up spending the day repairing the home AC. Sunday replaced the fuel pumps and filter in between heavy rain storms.


I went to start the car and...nothing. Literally...nothing. Just two messages..."ESP malfunction" and "ABS malfunction". WTF? It was running fine when I parked it! I only changed the fuel pumps and filter! Raised the hood to check the fuel pressure gauge and saw... standing water in the SAM and filling the connectors of the ECU. Storms dumped 2.5" of rain between my start and finish of the job and every bit of it went into the SAM and ECU. Connectors literally were filled with water. F**k. Me.


I sprayed all connectors and SAM with Safety Wash, then pulled each connector, all fuses, all relays. Sprayed WD-40 and then re-sprayed with Safety-Wash. Opened the ECU and dumped 1/4" of water out of it. Sprayed, dried in the sun, and then opened up the ABS unit and cleaned the connectors on it. Disassembled the SAM as much as possible in the car; pulled connectors, pulled cover, more WD-40, more Safety-Wash, then began reassembly after letting everything sit in the sun for an hour or so.


Everything reassembled, cross fingers, insert key, crank engine (which it would not do earlier), fuel pump engages, and the engine starts with no MIL! Yee-haw! I'll clear the stored codes later. For now, I'm just glad I dodged a very expensive bullet.


Moral: keep the plastic cover on your SAM/ECU box at all times!


Hope this tale of woe and redemption helps someone else out.