Fault code : P0174 ?? What is this ?

C

crabbes

Member
 Rugby. Warwickshire
Hi all
This fault code has been appearing now over the last few weeks, I can delete it using my fault reader but it comes back after running for about 30 miles or so.

Can anyone tell me what it means and how I would be able to fix the problem and a rough price please, is this causing damage to the engine if I continue to drive the car which is a 2004 reg 2.2 Z4 roadster,I have checked the hoses for splits and leaks and all seem OK.
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I have the same on mine- think it may be the DISA, will let you know as Im going to book it in with bmw as I still have the warranty on my 2.2.
 
GuidoK said:
paddy wright said:
I have the same on mine- think it may be the DISA,
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I think thats highly unlikely?
Why do you think its the disa?
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It's well documented that the disa can throw this code, mine is also now rattling which would also suggest it may be failing. This leads me to suspect mine is the issue. If the OP has no leaks in any hoses it must either be the DISA or the MAF failing.
 
Only if the disa causes a vacuum leak it can throw this code imho. Either with a bad rubber seal or thats it's broken in half or so.
The disa self doesnt throw this code, it's always a leak.
Its probably vacuum leak, faulty MAF, faulty lambdasensor or a clogged up injector/something with the fuel feed.
Either way, replacing the disa isnt the first step you do to trace a vacuum leak. replacing parts without diagnosis can get really expensive really fast.
 
GuidoK said:
Only if the disa causes a vacuum leak it can throw this code imho. Either with a bad rubber seal or thats it's broken in half or so.
The disa self doesnt throw this code, it's always a leak.
Its probably vacuum leak, faulty MAF, faulty lambdasensor or a clogged up injector/something with the fuel feed.
Either way, replacing the disa isnt the first step you do to trace a vacuum leak. replacing parts without diagnosis can get really expensive really fast.
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I understand this- which is why I said I would update the OP after mine has been to BMW as they will diagnose and trace the cheapest to them route. I would never suggest replacing such an expensive part as a first port of call.
 
ok I understand.

Still a vacuum leak is the most/ a probable cause. There are I think some grommets at the end of the manifold (so on the side that faces the bulkhead of the passenger cabin) that plug off holes that can degrade over time.
Spray with some brake cleaner when idling (or blow with an unlit propane torch (you need the gas)) to see if it changes revs if you want to go and hunt down vacuum leaks yourself :)
 
Thanks for the info Paddy, would you know the rough costs of this replacement, I know yours is under warranty but wondered if they had given you any info on this. :thumbsup:
 
crabbes said:
Thanks for the info Paddy, would you know the rough costs of this replacement, I know yours is under warranty but wondered if they had given you any info on this. :thumbsup:
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New part is around £200 but you could just repair yours for £50 with a repair kit.
https://www.germanautosolutions.com/diy_tech/disa_repair_kit/m54_disa_kit_diy.php
 
Can anyone recommend someone to fix this problem for me, Or a BMW mobile mechanic, I am based in Rugby Warwickshire. :thumbsup:
 
There are 2 problems with the DISA. One is the rattle which means its about to fail, if this is the case - fix it! The other is the gasket which is rubbish and leaks.

If you want to try a cheap fix, this is what i did recently and the car feels much better for it (i had whiteish spark plugs so could tell it was running a little lean):
1. Remove DISA (easy, lots of guides)
2. Clean the mating surfaces of the DISA and Inlet Manifold thoroughly using a solvent which wont leave a residue like Brake Cleaner or white spirit. These are the parts where the orange gasket touches.
3. Apply a coat of gasket sealant to the circular gasket to ensure it seals correctly - use a small amount making sure it wont interfere with the DISA flap and wont seep into the inlet manifold. You could also apply this to the other orange gasket but i didn't bother.

Also make sure your intake boot isnt split (google it for pics). If it is, you can also temporarily seal this with gasket sealant to troubleshoot.

Good luck :)
 
Thanks Ed for your reply, I do not feel confident doing mechanical repairs and would prefer someone experienced to look at it.
 
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