S4 B6 secondary air pump wiring repair

[Dondbg]

This probably been covered lots of times as it a common issue.

In summary the secondary air pump wires coating / insulation is flaking, all metal is exposed, short, KABOOM!

Each S4 B6 I owned got the same issue.



So since this been covered heaps of times I would like to ask what would be the best repair approach?

I’m thinking to cut the ground at the firewall and the positive at the relay under the ECU and pull both out of the engine wiring loom, now the new ground simply will grab a connection from the nearest point to the pump and run new wire for the positive just direct through the firewall. I do not see a point of ripping open the engine wiring harness just so to pass new wires or pull new wires through it.

And What wire gauge you guys recommend ?

[Atomic Avant]

I don't have any recommendations atm since I am traveling for work. But this is an interesting topic to me.

[VinnysS4]

Pull wiring harness, remove the loom. Replace the wires, and wrap with high heat Tesa tape. Very very common problem


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[Dondbg]

Pull wiring harness, remove the loom. Replace the wires, and wrap with high heat Tesa tape. Very very common problem


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So you guys actually run new wires inside the engine wiring loom ?

[VinnysS4]

So you guys actually run new wires inside the engine wiring loom ?

Absolutely. From the factory they must have had a shitty batch of wires that they used for the SAI system because I have seen TONS of these with the insulation cracked or completely destroyed. Use 10ga wire and you should be fine. 12ga would probably work fine. The pump only runs for a minute or so on cold startup, but as it ages, the pump pulls more and more power.
I have actually seen 2 people recently with this EXACT problem.



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[Dondbg]

Absolutely. From the factory they must have had a shitty batch of wires that they used for the SAI system because I have seen TONS of these with the insulation cracked or completely destroyed. Use 10ga wire and you should be fine. 12ga would probably work fine. The pump only runs for a minute or so on cold startup, but as it ages, the pump pulls more and more power.
I have actually seen 2 people recently with this EXACT problem.



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Ya I have wreaked 5 S4’s all with the same issue.

I feel bad cutting the engine wiring loom to pass new wires .... damn

[VinnysS4]

Ya I have wreaked 5 S4’s all with the same issue.

I feel bad cutting the engine wiring loom to pass new wires .... damn

You could run them separate. It doesn’t really matter. I just like OEM fit/function on some things.


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[Atomic Avant]

I haven't been under my car yet to check mine. But now I want to. Is the wire run pretty straight forward to follow? Or am I removing most of the loom?

[Dondbg]

I haven't been under my car yet to check mine. But now I want to. Is the wire run pretty straight forward to follow? Or am I removing most of the loom?

It goes inside the engine wiring loom but you can check out at the pump terminal

[VinnysS4]

Most of the time the damages is not visible or barely visible. My friend had this repair done in less than two hours from start to finish and he has never touched a wiring harness before.


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[Atomic Avant]

That's good to know that it is straight forward. I don't have a lot of time between trips with work and I can't afford to have any crazy down time.

Now to see what I need to order.

[Kambesama]

Luckily when I did this my exposed wire ended right at the junction where the O2 sensors, MAF and some other wires met. I cut the loom open and redid the SAI pump wires from there. New wires each individually wrapped with multiple multiple heat shrink tubes before being wound back together as a loom and shoving it down the hole. Mine got exposed when I went to change a coolant pipe, I removed the air cleaner box for space and during that movement, I had to reposition the wiring out of the way. I suspect the movement and bending caused the brittle wires to break and touch. Stupid design for the "environmentally friendly" Biodegradable wiring.

https://www.audizine.com/forum/showt...4-today/page80
Post #3165 is what I did for mine. I reused the original pins by cutting them off and soldering it to the new wiring harness.
https://www.amazon.com/TICONN-Connec...3462056&sr=8-5
These things are pretty nifty, heat-shrink, and solder all inside. The heat-shrink is pretty thin so I doubled down with the marine-grade ones from harbor freight. Besides that, it's fairly straight forward.

[VinnysS4]

Luckily when I did this my exposed wire ended right at the junction where the O2 sensors, MAF and some other wires met. I cut the loom open and redid the SAI pump wires from there. New wires each individually wrapped with multiple multiple heat shrink tubes before being wound back together as a loom and shoving it down the hole. Mine got exposed when I went to change a coolant pipe, I removed the air cleaner box for space and during that movement, I had to reposition the wiring out of the way. I suspect the movement and bending caused the brittle wires to break and touch. Stupid design for the "environmentally friendly" Biodegradable wiring.

https://www.audizine.com/forum/showt...4-today/page80
Post #3165 is what I did for mine. I reused the original pins by cutting them off and soldering it to the new wiring harness.
https://www.amazon.com/TICONN-Connec...3462056&sr=8-5
These things are pretty nifty, heat-shrink, and solder all inside. The heat-shrink is pretty thin so I doubled down with the marine-grade ones from harbor freight. Besides that, it's fairly straight forward.

I used to absolutely swear by those “all in one” solder/shrink connectors. Then one of my favorite YouTube mechanics was talking about how he used to use them all the time; Until they started coming back Due to wiring issues. I’ve yet to have a failure with one, but it something to keep in mind.


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[Kambesama]

I to have had issues with these in the past but that was due to me not being thorough. It has to really be melted down till you can see the wires through the solder. I also make sure to push the wire into each other vs "tips" touching. Being meshed together and then solder to bind them have resulted in a 0% come back when I do any wire repairs. I also love how I can change the size just by cutting more of the heat shrink off to fit small areas or bends. Love using these on those older BMWs where the wires break in the trunk harness.

[VinnysS4]

One thing I do that gives me peace of mind when I use them, I take the tip of each wire and bend it backwards on itself 99%. Basically creating two fish hooks. Then when I push the wires into the heat shrink connector, I pull on them just a little bit so the they Dig into each other. This creates a good mechanical connection before I solder them.


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[The Pope]

I just did mine. It was easier than expected. You do not need to cut anything open. You sline the rubber fiber covers back, undo the tessa tape in each section and then pull the wires out. Blow out with a high pressure air hose all the old plastic in each section. Then feed the new wire through each section at a time. You will need about 10'-0" of wire of the two colors. Then put new tessa tape on each section as before. Get the tessa tape rated for exterior 300 deg. Hit me up for pics.

[Dondbg]

Last night I have pulled the ground and cut the positive but didn’t pull it all, I have left it there and will just run separate new wires outside the engine harness, don’t want to cut it, no point.

I have noticed actually the wires are melted



Still will reuse the plug

[88jay88]

I realize it's been a while since this thread was updated but wanted to just point out that I have found that the terminal part number is VAG - OE-N 907 327 03. You are not going to easily get those off the old wires. All the dimensions shown here in the second picture line up with the SAI terminal measurements I took. https://www.onlinecarparts.co.uk/her...s-1673335.html