GBW

I'm looking of some assistance with the infamous 16795 Secondary Air Injection Incorrect Flow DCT.

From a background perspective, I picked up a 2000 1.8t 5 speed (ATW Engine) with 145,000 miles in August to use as a track car. No codes were present at that point, but I did notice that some of the vacuum hoses were frayed and sure enough about a week after purchase, I started getting some 16795 and 17536 codes.

Using the archives, I replaced a number of vacuum hoses, including:
- between the Combi valve and N112,
- between the Combi valve and the Secondary Air Injector motor
- between fuel pressure regulator and the intake manifold

With these changes, I was able to pass emissions and drive for several weeks during the fall with no additional codes. Unfortunately, in Connecticut, it begins to get cold in the fall and I started getting some intermittent 16795 codes (no other codes have been thrown since the summer) as the temperatures got colder, as we've transitioned to Winter, the code is on all the time now.

Based on research done in the archives, I'm focusing on the following potential issues:
- Additional vacuum hose issues
- Combi valve issue
- N112 valve issue
- Secondary Air Pump issue

This afternoon, I double checked all the vacuum lines visually using a mirror, and they looked fine. I also checked that corrugated tube that goes down to the Secondary Air Pump which looked fine. I was planning to hook the Secondary Air Pump directly up to a 12 volt battery to validate that it was working, and when I disconnected the corrugated pressure hose between the Secondary Air Pump and connecting line (I disconnected at the output/compressed air end) several tablespoons of water came out of the tube. Would this be normal? Unfortunately, I was unable to unplug the electrical connection from the pump so I could not test it. Bentley mentions that I should validate the fuse is good, but the Secondary Air Pump is not listed on the fuse panel.....everything electrical on the car is working however. Anybody know what fuse? The battery is a new Audi battery.

I pulled out the VAG-COM and ran the Output Test with the following results:
- EVAP Purge Valve (N80) - Hum and click sound
- Secondary Air Injector Solenoid Valve (N112) - hum and popping sound
- Secondary Air Pump Relay (J299) - clicking sound
- Boost Pressure Regulation Valve (N75) - tap and click sound
- EVAP Leak Detection Pump - squeak sound
- Boost Pressure Control Valve (N249) - clicking sound
- Fuel Injector 1 (N30) - click
- Fuel Injector 3 (N32) - click
- Fuel Injector 4 (N33) - click
- Fuel Injector 2 (N31) - click

Everything passed the Output Test.

I'm a little suspicious of the N112 as I had run that test a month or so ago and the noise it made was very faint; it was louder today.

So, I'm back to suspecting the Combi Valve, N112 and Secondary Air Pump (in that order)....but what about that water draining out of the Secondary Air Pump....normal condensation?

If it's the N112 or the Secondary Air Pump, what's the best way to get access to those to do a more through checkout?

Where would you recommend I begin to dig a little deeper? Is there a better way to approach this? What would you think would be most likely to fail?

TIA!

Allroady DungBeetle

Do you hear that?

If not then you'll need to dig a little deeper. It may be the control not signaling it to run - but probably it's the motor if it's not running.

The water is normal as long as it's only a little - no worries at all.

The car starts and runs fine when stone cold?

Carson@RiversideAudi

What happens is when the Combi Valve fails, the water present after combustion in the exhaust makes its way into the secondary air system and prevents it from operating.

058-131-101-B VALVE $110.97
078-131-120-K GASKET (2 needed) $2.97 ea

All prices above reflect the AW discount.

Allroady DungBeetle

I thought a very tiny bit was normal.... *learns something EVERY day!* ;-P

quicksilver 2.7

Is there a fuse for the sap?

ThunderAlley

did you get this solved?

GBW

Yes, replaced combi valve, which had failed letting water into the SAI Pump, which failed due to the water and resulting corrosion, then replaced the large fuse in the ECU which blew due to the corroded SAI pump that would not turn. About $500 in parts, but no codes since then and it's a year later.