Skoda Power!

Secondary Air Injection System Removal

I scanned my car a couple of weeks ago and it's logging the following:

16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-10 - - - Intermittent

Which is an excuse for removal Especially as I plan to de-cat.

All it does is inject extra air when the engine is cold to make the cat more efficient for the first 60-90 seconds of running.
Mine's been getting noisy which is a common fault apparently. The rivets holding together the two halves of the pump are prone to failure.

Secondary Air Injection Pump

You can see only one of the three visible rivets has a head.

Removal saves about 3kg in weight

Part 1

-Blank off hole in filter box (Not applicable as I have a CAI)
-Blank off hole on cylinder head (with Forge plate), after removing the combination valve
-Remove secondary air pump, 2 long black plastic hoses & engine mount bracket
-Add resistors to fool the ECU into thinking the electronic bits still exist

Part 2

-Remove N112 from the vacuum system, which controls the combination valve
-Remove the relay from the relay box in the engine bay

Guide:- Removing Secondary Air Injection - SEAT - SEAT Forum

| Passives | Resistors, Potentiometers or Control Knobs | Resistors, Fixed Discrete | Aluminium Housed, Wirewound -10 to 600W |HS10 330R J

Forge Motorsport | Alloy Fabrication

Secondary Air System

Another diagram showing the parts removed in part 1 (red), part 2 (blue) and the N249 system - as it's somewhat intertwined! (Orange)
Secondary Air System Diagram - Coloured



Here's my highly professional diagram:

This diagram took hours to draw 
Blue is the catch can and fittings, red is the secondary air system.

Secondary Air Injection System Removal - Part 1

Part one of this job is done. I was incorrect in my scribbles above - the reservoir on top of the engine is for the N249 valve not the secondary air system.

Tools you will need are:
8mm and 5mm allen keys or allen attachments for your socket set.
Socket set with 10mm socket and extension bits to make life a bit easier!
Torx driver - T20 I think

These are the parts to fit:


The usual Before shot:

First job - jack up the car and get it safely propped on axle stands.

Remove the front plastic under tray by removing the four torx screws - two at each side

This allows access to the pump - to the left of the engine bay at the bottom. It's attached to a large black bracket by three screws:

Now that it's loose, disconnect the power connector and two air pipes so that you can you can wiggle it around to get to the two 8mm allen bolts holding the bracket to the block. The pump won't come out of the bracket yet.

I didn't have an 8mm Allen bit for my socket set so I used an improvised tool to get the leverage to loosen these.IMG_1442

Much cursing was required but they eventually came free! Once the bottom of the bracket is loose the pump will come out.
I couldn't shift the top bolt so for now the bracket is still attached - an 8mm allen bit for my socket set is on order!

Next job is to install the resistor to convince the ECU that the pump is still there. You'll get "pressure low" type codes but not a full "pump failed" one.
The pump connector has two spade connections so I made this:

 In place - looks well dodgy!

Wrapped up:

Okay that's all the under-car work for now so put the cover back and lower the car off the stands.

Oh no I dirtied it:

Next job is to remove the air pipes. Undo the two 10mm nuts holding the pipe in place:

And pull the pipes up and out of the way.

Undo the two 5mm allen bolts holding the metal tray in place. Carefully ease it forward and lift away from the oil filler tube. The tube is apparently easy to snap, so only ease it forward as far as you need to, to lift up the metal tray, Once it's out you can flip it over to undo the final 10mm nut holding the air tubes in place.

At this point I re-fitted the plate as I'll come back to the N112 later.

Next is to remove the combi valve and fit the Forge blanking plate. Here's the valve:

You can see in the following picture that one of the the water pipes blocks the allen bolts holding the valve in place. You need to remove two 10mm nuts to free the water pipe and allow access. When you do this, lots of water will come out :) The red arrows show the approximate location of the nuts:

On the back of the valve is a black metal bracket, and attached to this bracket are two plastic clips holding a wire in place. I found these to be an absolute pig to remove, and the valve won't come off without removing them. They are push-fit plastic clips that go through holes in the bracket. I freed them by pushing them back through from the back of the plate using a screwdriver.

Once they're free the valve just drops off. Un-clip the rubber hose from the back and you're done:

You can now re-fit the water pipe and attach the Forge blanking plate:

For now I screwed a self-tapper into the end of the pipe to seal it:

And there you go - slightly tidier engine bay:


This is everything I removed - and the bracket will follow later:

Secondary Air Injection System Removal - Part 2
N112 Removal

So far I've just disconnected the N112 like so:
The underneath of the plate which holds the N249 and N112 valves. N249 in the centre, N112 to the right. The top line feeding to the N112 is the one I capped off at the other end where I removed the combi valve.

The resistor

In place - I taped up the connector end and cable-tied the resistor to one of the pipes so it's free to cool.

Again I capped the end of the pipe with a self-tapping screw. Need to get an elbow to replace the T-piece into the N249 and tidy things up.

No further fault codes yet - one cold start and an hour or so's driving so time will tell.