Code 377A and Overheating!!!!
Code: BMW 377A: engine cooling system has switched off the electric coolant pump due to a blockage or mechanical seizure
Just moved to Florida and my 2013 335i E93 (120k miles, been running stage 2 mhd tune) definitely felt the heat. Car overheated one day and coolant started to spill out. Towed to mechanic and he quoted me 4k to replace the radiator and upper hose.
So obviously I towed it back to my place to do it myself. Got the new hose and radiator it but when I poured coolant back in and started to bleed the system while hooked up to a battery charger.
For some reason the bleed was taking 20 minutes and was still going, I heard the pump still running and saw coolant still flowing into the expansion tank. Drove around a bit and still got engine overheated warnings and 377A code.
I tried the bleed again but left it running for much longer, after 25 minutes it was still bleeding so I left to go eat and came back 20 minutes later and the ignition was still off (battery not the issue hazards were still on and battery charger says battery was at 100%).
When i turned the ignition back on the bleed started up right away.
I stopped the bleed after another 20 minutes and cleared the codes. The 377A code comes back right when I start driving again.
My mechanic thinks it is the thermostat, I hear and see the pump working when I bleed the car.