[RIP_MKVI]

Hi there, I got an engine overheating warning today on my 2012 335i. I had the same issue two months ago and replaced water pump and thermostat. I m not sure why it happened again so soon....this time the fan was not going off crazy like last time. Any thoughts?

[bbnks2]

Originally Posted by RIP_MKVI

Hi there, I got an engine overheating warning today on my 2012 335i. I had the same issue two months ago and replaced water pump and thermostat. I m not sure why it happened again so soon....this time the fan was not going off crazy like last time. Any thoughts?

Yeah.. scan for codes?

[NRigs]

Originally Posted by RIP_MKVI

Hi there, I got an engine overheating warning today on my 2012 335i. I had the same issue two months ago and replaced water pump and thermostat. I m not sure why it happened again so soon....this time the fan was not going off crazy like last time. Any thoughts?

This isn't too reassuring. I just dropped my car off at the shop to have the water pump and thermostat replaced for the overheating warning.

Hopefully I will get more than 2 months out of this...

I would make sure they used the newest revision water pump.

[RIP_MKVI]

Not entirely sure what is causing this...the radiator fan wasn't going full blast at all. Had to turn off and restart the car at every red light to drive it back home today...will take it to dealer on Tuesday to find out more

[Cory S]

You can narrow it down to a coolant FLOW issue, or an AIRFLOW issue. Does it overheat when cruising at a constant 30+mph, or only when driving slow such as stop lights in the city?

If it only overheats when moving slowly or stopped, you have an airflow problem. Which would be your fan most likely.

Check cold coolant level, and any signs of weeping coolant.

[mr.melanson]

I am having a somewhat similar problem and if anyone wants to chime in PLEASE do! I got the engine overheat warning so I pulled over, let it cool and made my way to the shop. They said the water pump was working fine but after more testing they found the sensors were detecting much higher temps than they really were. They tried new sensors with no luck. They replaced the fan and fan assembly with no luck. I have a jb4 ISO but I've been running it for almost a year now so there's nothing new there. The shop thinks try removing the jb4, if that doesn't work take it to the dealership for a software update, and if that fails they said maybe I need a new DME which is $2300!!! I'm going to try some troubleshooting with the jb4 tomorrow and ensure I've got the latest software for that as well.

[aaron_]

I was told I might need a new DME. Took out jb4. No problem. Get on mhd.

[RIP_MKVI]

Originally Posted by Cory S

You can narrow it down to a coolant FLOW issue, or an AIRFLOW issue. Does it overheat when cruising at a constant 30+mph, or only when driving slow such as stop lights in the city?

If it only overheats when moving slowly or stopped, you have an airflow problem. Which would be your fan most likely.

Check cold coolant level, and any signs of weeping coolant.

You sir are exactly right. It was airflow issue. I took the car in to the dealer and they weren't able to read the code due to JB4 cleared them up. They checked the coolant, did a pressure test and turns out OK, I picked up the car today drove for a few minutes and the overheating warning popped up again, I was going to remove JB4 and bring the car in again, but the warning went away after I got on freeway. I took it to a inde shop and they immediately noticed that the main radiator fan is not working at all. Gonna tow the car to dealer again next week to fix that.

Thanks,