Bad combi valve? Picture

[todda7]

Got some VAGCom errors complaining about incorrect SAI flow. The pump is definitly broken, but the combi valve isnt supposed to look like this, right?

[spyder101]

If you have vagcom, I would replace the pump first and then run a basic settings on the secondary air injection system. Do this first before you replace the combi valve (it may past the test and save you some money in the short run). The combi valve does look a little coked up though.

[Seerlah]

My combi valve def didn't look like that when I took it off with maybe 120k (miles) on it. Sold it and person I'm sure had no problems with it because he never contacted me (I believe in customer service). I would go the route of getting it coded out of your ECU, throw a block off plate on it, and ditch your SAI.

[todda7]

Can I code it out of the ECU myself with VAG-com? Will it still pass emissions?

[Seerlah]

No, you need to to have the coding in your ECU for your SAI remapped. It will still pass emissions if coded properly. You will still pass readiness and have no CEL. Even if they do the exhaust gas combustion test, you should still pass. There is an Audizine member in Norway who may be able to lead you in the right direction to get this done, if you want to go this route. Send him a PM.

http://www.audizine.com/forum/member...3391-Nollywood (well, I believe it's him who is from Norway. there are a few more I can't remember off the top of my head right now)

[todda7]

I can't find anyone who can remap the ECU, so I'll just get a cheap knock-off SAI pump and keep it unplugged until emissions test. I seem to remember reading somewhere that no SAI-flow will ruin the catalytic converter, do you know if there is some truth to that?

[SN95Audi87]

I am still getting this code, and I had the car for 4 years. Pump turns on, and vac lines have been replaced.

[walky_talky20]

No it doesn't damage anything. The cat just warms up slower.

The system is very simple and there are only a few moving parts: the pump (and the relay that drives it), the combi valve (and the vacuum switching valve that drives it), the piping that connects those 2, and the oxygen sensors to sniff the exhaust stream.

If your pump is pumping, and pipes and lines are good, make sure your combi valve is actually opening and closing on command. The normal failure is that they stick in one position or the other. VCDS output test on the N112 solenoid valve is usually sufficient to check this. The combi valve sounds distinctly like a plunger during operation.

[todda7]

Yea, I did the test in VCDS. Both the relay and the solenoid valve clicked noticeably, but the pump did not start and on visual inspection in turned out to be quite bashed. I'm gonna pull it out and hook it onto a 12V source to see if it starts. By the way, could a broken SAI pump cause the 'No activity' DTC on the rear O2 sensor?

[SN95Audi87]

No it doesn't damage anything. The cat just warms up slower.

The system is very simple and there are only a few moving parts: the pump (and the relay that drives it), the combi valve (and the vacuum switching valve that drives it), the piping that connects those 2, and the oxygen sensors to sniff the exhaust stream.

If your pump is pumping, and pipes and lines are good, make sure your combi valve is actually opening and closing on command. The normal failure is that they stick in one position or the other. VCDS output test on the N112 solenoid valve is usually sufficient to check this. The combi valve sounds distinctly like a plunger during operation.

What block you have to run to activate this test?

[todda7]

Go to Engine Module, Output Tests, then click next, and there should be two tests, one for Solenoid Valve and one for relay which should also activate the pump. PS: You have to start and stop the engine in order to rerun the test. Useful video for SAI diagnosis

Walky: Is it the solenoid or the combi valve which makes the clicking sound during the solenoid valve test?

[walky_talky20]

Solenoid makes a click noise, as well as a "shhhh" noise when vacuum is vented to atmosphere. The combi valve makes a "thunk...plop...thunk...plop" noise, like a plunger.