P0491 code (Secondary Air Injection System Insufficient Flow Bank 1)

[stevekstevek]

I've got a 2008 E93 M3 with a VF620 kit installed. Just bought the car 6 weeks ago.

I've had a few Codes being thrown -- first it was the O2 Sensor heater (sensor 1, bank 1). I replaced the O2 sensor, and that's all good.

Now, I'm getting this code. I've cleared it a few times, but it seems to come back pretty regularly.

I'm guessing the pump actually works, otherwise I'd get codes for both banks. So it could be either faulty tubing connecting the pump to the manifold, or a faulty valve?

Haven't dug into the system yet, but I'm wondering if I can even reach it without removing the whole manifold. Since the car has the supercharger, doesn't seem like it would be good to try to run the car without the manifold on it, so if I can't get to these things, what's the best way to diagnose?

How hard are the valves and pump to get to?

[takrdown]

I'm interested in this as well. I had the same issues and never really resolved them. I also have a VF620 supercharger....hmmmmmmmm. Mike Benvo might have some insight but I was working with him and we both moved onto other things before we really looked into it.

[stevekstevek]

Hmm, just realized I should probably have put this into another thread.

It looks like I can see the pump around the VF620 manifold, but can't really get a good look at the tubes.

Also, Bank 1 is on the passenger side, so there's a little more room there (almost stock amounts of room -- just the hoses from the intercooler are over there).

Still I can't really see the hoses from up top, or at least I can't identify them. I think the best way to see the secondary air valve and hoses might be to lift the car and drop the skid plate (again -- just did that for the O2 Sensor).

This is all on the exhaust side of the engine, so I don't think the VF620 has a lot to do with it, though we are running their custom tune which does who-knows-what.. The O2 sensor I pulled was pretty carboned-up, so I get the sense that it runs rich, at least until closed-loop. So, since my O2 sensor heater wasn't working for 1,000 miles, I'm guessing it was staying in open-loop for a while.

I just passed inspection, so the good thing is that for the next year, this is likely only going to annoy me with the SES light. If I'm going to take off the manifold and start messing with parts, I think it's probably a good time to change plugs too, since I have no idea when/if that was ever done.

[takrdown]

I'm running a BPM tune so I don't get the SES light for it anymore.....I recommend it if you're looking to upgrade and for much better support than you get right now.