2008 328xi SES Light On from "High Engine Temp"

[jmd_forest]

2008 328xi is NOT under warranty or I would be at the dealer for this. It seems that after 3 incidents of "High Engine Temp" (over 90 degrees C) the SES light goes on. It can be 1000 miles between incidents or about a month between SES lights. Highest temp recorded is 101C engine temp. Since my Mercedes temp gauge starts to redline around 125 C I'm not worried YET about overheating damage. I've cleared it twice so far and just replaced a faulty outside air temp sensor (it may or may not be related). No other codes are thrown (Using Bavarian Technics reader). Radiator is from a 2006 325 with the temp sensor transplanted from the original radiator which was damaged. There are no coolant leaks. Thermostat and thermostat housing are new.

Since there is no temp gauge its hard to tell what/when this is happening until the SES light goes on.

Any ideas (other than replace the radiator cludge with a factory radiator with embedded sensor, which is my next step if it happens again)???

jmd_forest

[jmd_forest]

Actual fault code was "2AD8" (I'm assuming hex or 10968 decimal) Anyone able to help with describing this code.

jmd_forest

[Andrew@FCP]

I would make sure the radiator is working. Take an inferred temp reader and see what the radiator temp is when the cooling fan turns on. If it keeps going over 90, then the radiator is not doing it's job and needs to be replaced.

[E46330iguy]

These engines are much tougher than people Give them credit for if the engine over heats once or twice that Peanuts for the block

[jmd_forest]

It turns out the 2AD8 code is "EAC Sensor Monitoring". There is an SBI 121607 for vehicles produced before 8/2007 with a fix of "update Progman ro newest version". The SBI notes an "implausieble difference in temps" at startup. Since my car was produced 4/2008 and I am seeing the SES light come on while running I am considering this a clue rather than the fix.

I have since determined that the radiator for the N51 engine in my car has more differences from the 2006 325 radiator than just the sensor I transplanted so I've ordered a new radiator from the dealer (way too much money) that has a new EAC sensor built in. I'll keep the thread posted as to how things turn out once the rad comes in.

jmd_forest