M235i battery drain, electric water pump constantly on?

[Clutchy123]

2014 M235i with 39k miles

Bought the car last week privately, battery was flat when I woke up this morning had to get AA to get me started.

Car tested and was found to be charging fine and the battery (AGM) in good condition just needed a full charge.

Discharge draw was 0.15 amps

However since owing the car it never wants to go into stop start despite all the other requirement (engine temp etc met) which could only leave insufficient charge being the reason it won't go into stop start in eco mode or any other mode.

Now I bought a decent trickle charger went to put it on and an hour after the car had last been turned off I could hear water being pumped around the engine (not leaking) sounds like the water pump was engaged as shown in the video.

I also opened the water resoviour to see water being squirted in at high pressure.

This must be causing a massive drain when the car is off, however it wasn't doing this when tested this morning

Any suggestions?


Link here https://youtu.be/4olO-xw5nfU

[corradokid]

I would say 150ma is too high a drain if the car is fully shut down. I’d also imagine that the coolant pump running after shutdown is standard practice but I don’t know much about your model. You may have already done so but would be worth a google to see if you can find Bmw quiescent specs but I’d expect it to be around 40ma.

Quick edit: missed the bit about the pump still running after an hour. I’d say that’s too long. Maybe a temp sensor issue?

Edited by corradokid on Saturday 16th June 23:06

[Charlie Croker mk2]

My AGM battery was shot at 3 years old but I think I killed it as the car is only used for long trips so I had it on a trickle charger all the time but I only found out you should not use a charger that has not got a dedicated AGM program . Bought a new battery and coded it into the car as well as a new ctek charger.

[helix402]

As mentioned 35/40mA is the max drain you should see. When was the closed circuit drain measured as you have to wait a while for the car to go into sleep mode?

[Hcolon0413]

How do you resolve the issue? I have the same problem, the pump stays on with the car off, it drains complete the baterry, I replace the battery twice in less of 2 weeks and the same, replace the IBS cable from the battery and nothing. The mechanic said that it was the Ecu.

Any ideas or suggestions