Engine fan kicks on intermittently on cold starts

[paris1]

Once or twice a week and only on a dead cold start, the engine fan comes on immediately and stays on along with (what I presume) is the engine check light (engine symbol yellow on left and black on right). I shut the engine off, restart and everything is fine. No other symptoms. I know I need to check for codes, but I'm wondering if anyone else has experienced this and can shed some light on the cause. I'm thinking maybe a bad fan relay?

[rjahl]

Originally Posted by paris1

Once or twice a week and only on a dead cold start, the engine fan comes on immediately and stays on along with (what I presume) is the engine check light (engine symbol yellow on left and black on right). I shut the engine off, restart and everything is fine. No other symptoms. I know I need to check for codes, but I'm wondering if anyone else has experienced this and can shed some light on the cause. I'm thinking maybe a bad fan relay?

Need to read codes but my first guess would be a water pump on its last legs. Sort it out before driving too far from home.

[paris1]

Pump was replaced a little over a year ago.

[KennyP]

My first thought would be waterpump electrical failure aswell... first sign for that is usually fan kicking on.

Maybe replacement pump was defective? Just replaced my pump aswell due to plastic cracking on it. If that happens then fan wont kick on. You will lose coolant and get a low coolant warning inside. My thermostat was starting to crack aswell.

If not the pump then maybe coolant temperature sensor near the oil filter housing is the problem? Maybe bad connection or something?

[paris1]

Resurrecting old thread to give a heads up to those whose Z4 might suffer the same fate mine did. Symptoms: let the car sit for a couple of days (won't necessarily do this on every cold start) and start as usual. Engine fires off and then begins to stumble as idle speed falls. Engine cooling fan turns on and reduced power icon (black/yellow engine icon with slash through middle) lights up on dash as idle struggles to increase. Turn engine off and restart and all seems normal. Car drives OK, but there's been a noticeable decrease in fuel mileage as displayed on the dash over the last few weeks (dropped from 21.4 to 20 mpg in strictly city driving).
Problem turned out to be a failed high pressure fuel pump (even though this is a 2013 which had the revised pump and injectors after all the problems with the earlier cars). Dealer charged $1892 including quite a bit of diagnostic time. Car has 70k miles, so I guess the redesigned pump they used on the later cars is only good for so long. Tech mentioned that the injectors are ok, but that they are "index 09" and there is a newer version available (presumably for when they do fail!) No mention was made as to why the engine fan turned on in conjunction with the fuel pressure being too high on cold start (error code 2B2C), but two tsbs (13-13-10 and 13-02-20) recommended test procedures that verified failure.
This is only the second major repair I've had to pay for since the car went out of warranty in February of 2017 (never bought any kind of warranty extension). The water pump failed to the tune of $1300 about two years ago but I managed to recoup $1000 of that through the class action suit that was mounted last year. So I guess I should consider myself reasonably lucky.

[Marcoose]

Two large! Wow. Where’s the fuel pump in the E89? In the tank?

[paris1]

E89. Not sure where it is, but not in the tank. That's where the low pressure pump lives. I see you're in The City, so NorCal labor costs shouldn't be a surprise to you.

[Marcoose]

Yes, E89. Typo. My trusted indy is massively fair with his labour. Are you in the City as well? Where do you take your cars?

[paris1]

That's great. I tried an indie here in Santa Rosa after researching what was available and wasn't thrilled with the one I chose. The dealer here (Hansel BMW) has always treated me well and I have a good working relationship with one of the SAs, so I usually end up taking it to them. I've cross-shopped a few things over the years and there doesn't seem to be a significant price differential.

[KennyP]

Originally Posted by Marcoose

Two large! Wow. Where’s the fuel pump in the E89? In the tank?

HPFP is under the intake manifold , behind the alternator.
You have to remove airbox, intake manifold to get to it.
As it is very common fail item on N54 there are many DIY guides out there.
So you can replace it yourself. or Show those DIY guides to a indy mechanic with reasonable hour rates. I always email DIY guides to the shop i use to aid them and ofcourse have them finish the work faster so i would have to pay less.

One of the guides:
https://www.e90post.com/forums/showthread.php?t=654820

Its basically the same on e89 as on e90 or e82 etc.
One thing is different. 3 series etc have additional low fuel pressure sensor on the line going to the HPFP. E89 does not have it. Bmw kind of simplified things there on the Z4. Maybe something to do with Z4 LPFP being different in the tank.
Why i know that? Well my Cobb accessport showed low fuel pressure as 0 on its monitors. Found that to be odd and did some research.

This missing sensor shouldnt matter though.

Latest HPFP revision came out in Oct 2010. (13 51 7 616 170)
Part itself costs around 900 usd online.

For me in EU Hubauer-shop.de sells this pump online for 798 eur.

[Marcoose]

Thank you, lads. 👍