JJm64123

Hey all,

An issue that has come up with my car now is this secondary air pump. I am getting code P0411 and says incorrect flow detected. I recently replaced the air pump that was not working and found it to be full of water. So hoping that this was some issue that the previous owner tried to fix I installed the new pump and it seemed to work fine. Now a week of driving the car has gone by and now the check engine light is on again. I am desperately searching for a broken hose, and when I went to take off the outlet hose from the pump, water started to come out again. How is this happening? I don't see any openings that water can be getting in, but I think that could be the reason why I now have this code because air isn't flowing because of water getting in the way.

turbo510

The ECU determines that the SAI is working by watching the post-cat O2 sensor. So besides the pump, the SAI valve(s) have to work, the Cat(s) have to work, and the downstream O2 sensor(s) have to be OK.

W261w261

I have a 68k '04 1.8 Passat (my 2nd one - the first I ran up to 175k and dumped it), and for probably 5 years have had an '03 A4, running it from 100k to 160k. The VW's have regularly and aggravatingly gone through the SAI pumps, maybe because I buy the cheap ones from Amazon for $100 as opposed to the outrageous ones from the dealer for around $500. This, for a piece of equipment that runs for a couple of minutes upon a cold start. I just got a letter from the CT DMV telling me I'm fined $20 because I didn't get my emission check in time, which I couldn't do because the CEL is lit with the familiar "low flow SAI" message. I just drive around with the CEL lit because I'm too irritated to put on another ****in pump. Meantime with the A4, no problem ever.

Do you think this is because I buy POS as opposed to OEM? I tried to get one off a wreck a couple of times but you can guess how that turned out.

I never knew how the ECU could tell about the low flow, so thanks for that info. I once jiggered the O2 sensors on a friend's Nissan 3.5 with a resistor or capacitor to fake out the ECU so he wouldn't have to buy new cats. I wonder if I could do that with the Passat?

JJm64123

So I feel like I can rule out a vacuum leak because I don’t see any signs of broken hoses. But I still can’t figure out how water is getting into the pump. I understand the pump is the lowest part in the system but could water be building up enough from the exhaust and dripping forward to the pump? I never thought to see if the lines were connected that far. I guess I stopped searching up to the egr valve.

JJm64123

and just a side note, I ran 12v directly to the air pump to make it run and I soaked the vacuum lines from air box to the back of the engine and found no air bubbles. I don't know if that helps or not.

turbo510

Because the SAI pump can collect water due to an SAI valve that doesn't close completely, it seems to me that there should be a small drain hole in the hose so air pressure blows out any accumulated water. Simply having the air hose from the pump loop down enough to keep condensed water from the exhaust from ending up in the pump, or even a hole drilled in the lowest part of the pump housing. A little air pressure would be sacrificed, but it should keep the pump dry.

JJm64123

Would having a small hole in the line create a CEL situation?

turbo510

Depends on how big the hole and consequential air leak is. Considering the volume of air that pump can supply, I doubt that a 1/8" hole, in the lowest part of the blower housing, would make much difference on air pressure to the combi valve.

JJm64123

Thank you, I think I am going to try that so I don't burn out another pump. I am thinking since it keeps throwing a cel light code for incorrect air flow I should probably change the combi valve on the back of the block anyways. just sucks how expensive that part is and how inconvenient the location is.

laur78

I need some help with this electric issue that runs to the air pump
I activated the air pump through VSDS VagCOM and is running fine
When I started the engine is not receiving power from the ECM
What is going on?