# Water in Secondary Air Pump...



## folkswagon (Oct 31, 2007)

Hi all,

I've just finished putting new discs, pads, spark plugs and a v belt on my TT and whilst it was up on jacks decided to finally have a look at what was causing the following fault code on VAG COM -

16795 - Secondary Air Injection System: Incorrect Flow Detected

There's quite a lot of info on this out there, this is what I found about the fault on the Ross-Tech Wiki -

http://wiki.ross-tech.com/index.php/16795/P0411/001041

Description of the Secondary Air Injection system (and checking procedure if you have all the right VAG checking equipment!) -

http://www.vaglinks.com/Docs/Audi/TT/Audi_TT_Sec_Air.pdf

And an excellent guide on how to remove it from JAAYDE and further discussion on the TT forum -

http://www.********.co.uk/forum/viewtopic.php?t=97287&highlight=busy

http://www.********.co.uk/forum/vie...0&sk=t&sd=a&hilit=Secondary+Air+Pump&start=15

Anyway since I was under the car I thought I would unplug the Secondary Air Pump. Once the plug was removed a significant amount of very rusty water flowed out! That explains why I had never heard any hair dryer noises from my TT.

After a little searching I found this on a BMW 318ti.org forum...

_Q: I am having a problem with water getting into the secondary air pump. I am not sure if it is getting through the air filter somehow, or coming in through the exhaust. Either way, the water rusts the motor in the air pump and eventually it stops working.

A: The valve that lets the air from the pump into the exhaust has stuck open. Which allowes hot exhaust into the pump. when the car is shut off the pump cools and forms condensation inside the pump. Same as it does inside the exhaust. this leads to the air pump rusting inside and eventually locking up. We always replace the pump, valve and relay together. A fried pump will damage the relay, if not replaced it normally fails several months later. The valve is normally the cause of air pump failure._

Is this possible on the Audi system? Has anyone found similar problems on a TT or other VW variant? I want to repair the system rather than remove it. Since Steve_H states that 'Secondary Air pump is £275.00 plus vat alone... from Audi' I kinda want to have a go at repairing the old one so I'll try and keep this post up to date with how I get on.

Any tips or guidance on the way will be much appreciated 

Chris


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## conlechi (May 6, 2006)

Hi Chris,
not sure of the repair side but some have removed theirs with no problms , you would need a blanking plate and resistor , not too expensive

It will be something i will be doing

Mark


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## folkswagon (Oct 31, 2007)

For those wanting to remove the system here's a link for the blanking plate that will be needed -

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=010601&product=FMEGRBP

£18.74 inc VAT from Forge motorsport

I also found a link covering quite a good pictorial repair procedure on a noisy pump fitted to a golf -

http://uk-mkivs.net/forums/p/141240/1411070.aspx

I think that mine will need more extensive surgery based on the rusty motor internals, rather than the leaky blower side. It also looks like it's a bit easier to remove on the golf.

Depending on what I find I may go down the removal route, especially if I have to part with large amounts of cash but for now I'll try and do my bit for the environment :wink:

Does anyone have any thoughts on this system helping the cat last longer or any other potential detrimental effects of removing it, apart from the environment of course?

Cheers,

Chris


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## Wak (May 6, 2002)

one of the best precautionary mods you can do is to disconnect the pipe from the air box.

add a filter to the pipe and block off the hole on the airbox lid..... this will protect your air filter and air mass meter.


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## folkswagon (Oct 31, 2007)

Thanks for the tip Wak but what is the protection for? does a knackered secondary air system blow crud directly back into the intake? That may explain the MAF I've just had to replace! Suddenly everything is becoming clear 

Cheers,

Chris


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## Wak (May 6, 2002)

folkswagon said:


> Thanks for the tip Wak but what is the protection for? does a knackered secondary air system blow crud directly back into the intake? That may explain the MAF I've just had to replace! Suddenly everything is becoming clear
> 
> Cheers,
> 
> Chris


exactly and the air filters end up pretty wet,brown and crusty as well as the crap being sucked in over he maf.. :?


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## folkswagon (Oct 31, 2007)

Had another closer look at the Secondary Air Pump and found that it's fairly easy to unclip the back of the motor housing insitue and this is what I found -










You can just see the rusty coloured internals and the picture below shows the mess it left on the floor! -










I checked fuse 43, and the relay (located in the relay carrier below a cover, next to the MAF connector) and found no issues. I also noted that my TT (2000 model 225) didn't have the branch from the combination valve (10) to the vacuum diaphragm for charge air pressure regulation (7) as shown in the link that I listed for the TT's secondary air system description -

http://www.vaglinks.com/Docs/Audi/TT/Audi_TT_Sec_Air.pdf

I presume that there might be a few variations on this system but I'm kinda glad mine doesn't seem to have this extra branch as I was concerned that an in-operative system, especially a knackered combination valve for example, might cause some boost problems. I'm guessing that this extra bit was there to prevent full turbo operation before the engine has a chance to warm up, good thinking but problematic if the system fails me thinks :?

Anyway, looks like it's quite a major job to take the pump out as I'll need to remove the link pipe between the inter-coolers. For now I've just made the system safe by leaving the pump disconnected and plugging the connection to the airbox. Might carry out some checks on the combination valve and the N112 (solenoid) valve next as these are easier to get at.


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## folkswagon (Oct 31, 2007)

Thought I should update this one as it's been a while!

After much investigation I decided that for a system that Audi no longer use and one that it so susceptible to failing, it was definitely not worth the 300 quid to replace the pump.

Since the whole system weighs quite a bit I wonder if the benefit to the environment that comes from getting the CAT up to temp quicker versus the extra fuel burnt to carry the system throughout the life of the car is actually worth it?

Anyway for now I've successfully removed the old pump and blanked off the pipe work (Note for anyone planning the same it is important to blank the connection to the airbox or it will soon knacker the MAF as WAK pointed out). The plan was to completely remove the whole system and fit the Forge blanking plate but for now it will have to wait and as I plan to sell the TT now as my wife's got a set of twins brewing. I'll leave the final decision to the new owner.....


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## RSam84 (Jul 16, 2011)

sorry to drag a thread up from the depths but where is the secondary air pump actualy located? im removing my friends this week!


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