[JarvisTurkenton]

I consistently get this code… thermostat has been replaced by bmw dealer, both dealer and local shop say transmission coolant thermostat is staying open and is not getting up to temp… how easy is this to replace, looking at around $1,000 at shop… does anyone have a how to on this? Thank you.

[Opie55]

OK, I'll be stupid - what is an F25 328? There is a 28i (4cylinder) and a 35i (6 cylinder). I tried looking for you, but I need to know which engine you have.

[JarvisTurkenton]

Originally Posted by Opie55

OK, I'll be stupid - what is an F25 328? There is a 28i (4cylinder) and a 35i (6 cylinder). I tried looking for you, but I need to know which engine you have.

28i 4 cylinder sorry for the confusion, still new to bmw

[Opie55]

Assuming you meant 28i, I am a bit confused. The transmission cooler is located up front next to the fan, and is not too hard to get at. A new one is about $360 or so at online prices. But it does not appear that the one for a 28i has a thermostat. It just has coolant connections where the coolant freely flows through unregulated by a thermostat. But I could be wrong. Other BMWs do appear to have a thermostat as part of the cooler. Or maybe that was a 2015 change. Give me the last 7 places of your VIN and I'll look again.

[JarvisTurkenton]

This:

https://www.fcpeuro.com/products/bmw...BoCy7cQAvD_BwE

[pungo]

Originally Posted by JarvisTurkenton

This:

https://www.fcpeuro.com/products/bmw...BoCy7cQAvD_BwE

Can you link to one that's for your actual vehicle?

[JarvisTurkenton]

See attached

[pungo]

Originally Posted by JarvisTurkenton

See attached

That part # is for the entire cooler assembly
Should be a simple DIY, open the hood and take a look at it.

[JarvisTurkenton]

Originally Posted by pungo

That part # is for the entire cooler assembly
Should be a simple DIY, open the hood and take a look at it.

Can you do just the thermostat instead of the whole assembly piece?

[JarvisTurkenton]

Originally Posted by Opie55

Assuming you meant 28i, I am a bit confused. The transmission cooler is located up front next to the fan, and is not too hard to get at. A new one is about $360 or so at online prices. But it does not appear that the one for a 28i has a thermostat. It just has coolant connections where the coolant freely flows through unregulated by a thermostat. But I could be wrong. Other BMWs do appear to have a thermostat as part of the cooler. Or maybe that was a 2015 change. Give me the last 7 places of your VIN and I'll look again.

0d50391

[pungo]

Originally Posted by JarvisTurkenton

Can you do just the thermostat instead of the whole assembly piece?

If it's only sold as an assembly, why wouldn't you just replace the entire assembly

[JarvisTurkenton]

Originally Posted by pungo

If it's only sold as an assembly, why wouldn't you just replace the entire assembly

You’re right, whole assembly it is

[pungo]

Not sure why the shop says it's the trans cooler when the error is for engine coolant
I'd use ista+ to diagnose the problem before throwing parts that don't make sense at it.

[Opie55]

Still confused. If I look that up that part # on RealOEM.com it shows it's for an X5 or X6. No X3 application.

I agree with Pungo - you need to scan the codes with something that reads BMW codes, not just a generic OBDII scanner. Even if the car has a tranny thermostat, and even if it was stuck wide open, it seems odd it would give you an overall engine coolant error.

[Opie55]

OK, I looked with your VIN. Your tranny cooler is part number is 17217593856. If you google that number you will find numerous pictures of it - used ones on eBay, etc. You can see that it has an assembly that looks like the separate part you listed above - but I cannot swear it's identical. But no such part is listed as sperate from the entire assembly for an X3 - just the X5 - even though it obviously just bolts on. So possibly your shop knows something RealOEM does not.

[JarvisTurkenton]

Originally Posted by Opie55

OK, I looked with your VIN. Your tranny cooler is part number is 17217593856. If you google that number you will find numerous pictures of it - used ones on eBay, etc. You can see that it has an assembly that looks like the separate part you listed above - but I cannot swear it's identical. But no such part is listed as sperate from the entire assembly for an X3 - just the X5 - even though it obviously just bolts on. So possibly your shop knows something RealOEM does not.

Greatly appreciated… I’m getting the readout from the shop pending holiday hours to get the specific fix, but it sounds like the whole assembly needs to be replaced… I’ve tried to research the issue and short term driving consequences, I’m trying to replace it much sooner than later but need it as a daily driver for short distances… should be fine temporarily but obviously need to fix it as soon as I can, would you all agree or am I just stating the obvious?

[Opie55]

If I were you, I would ask them why they think it is that part. That's what is confusing about this whole thread. You give a trouble code for engine coolant and say that somebody thinks your tranny cooler thermostat is bad. There has to be more to it because that does not really compute. If I had a coolant temp code for the engine like that I would suspect the main coolant thermostat. It would not occur to me that it was the tranny cooler. If it were me I would just scan the codes myself. If you download BimmerLink to your phone and get a BT dongle you can read them yourself. See if you get any tranny codes. But you can live monitor your tranny fluid temps.

[Ivan67]

I had to replace my engine coolant thermostat on our 2014 2.8i @ around 40 k miles
BMW later sent out a recall for the part. I received reimbursement for the repair.
Might be your issue?

[okayr]

So I got this exact code and it was my transmission cooler. I had it in the shop 4(?) times for this. Once at the dealer, and two different independent shops. They all changed the engine thermostat and since it was an intermittent problem I couldn't know if it was fixed until it messed up again.

The last independent shop also changed the engine thermostat but I brought it back when it started up and they held on to it until it was correctly diagnosed. They only noted 1D2008 but it also had the P code.

Haven't had a problem since it was done early 2021.
So! OP, I would put money on it being your transmission cooler.
I definitely would get a quote from another shop. The independent shop I went to is not the cheapest but they almost exclusively service BMWs.

Edit:
From what I was told driving it was fine, but mine I don't believe completely failed because I could usually turn it off and on at a light and it would go away until it got cold again. I wouldn't do any extended driving though obviously. I dealt with it over like 6 months and there's no apparent damage 2 years and 30k miles later.

[Opie55]

Originally Posted by okayr

So I got this exact code and it was my transmission cooler. I had it in the shop 4(?) times for this. Once at the dealer, and two different independent shops. They all changed the engine thermostat and since it was an intermittent problem I couldn't know if it was fixed until it messed up again.

The last independent shop also changed the engine thermostat but I brought it back when it started up and they held on to it until it was correctly diagnosed. They only noted 1D2008 but it also had the P code.

Haven't had a problem since it was done early 2021.
So! OP, I would put money on it being your transmission cooler.
I definitely would get a quote from another shop. The independent shop I went to is not the cheapest but they almost exclusively service BMWs.

Edit:
From what I was told driving it was fine, but mine I don't believe completely failed because I could usually turn it off and on at a light and it would go away until it got cold again. I wouldn't do any extended driving though obviously. I dealt with it over like 6 months and there's no apparent damage 2 years and 30k miles later.

Interesting. Good to file away as an alternative cause for low engine temps. They obviously replaced the whole cooler assembly. That is some serious markup on LifeGuard 8 tranny fluid. Online it runs about $25 a liter. Your shop got it wholesale and charged you $45.