Secondary air injection system driving me nuts

ThreeGermans · #1 08-28-2025, 03:43 PM

Sorry that my first post is a cry for help...

This is a fairly new-to-me 2006 X5 M5 (e53 with m54 3.0L straight 6 gas engine). I bought it a year ago and put 5000 miles on it.

As of 2 months ago, I keep getting Check Engine Light with codes P1419 (split air #2 circuit malfunction) and/or p0491 (secondary air injection system bank #1 malfunction- insufficient flow).

I sprayed the secondary MAF (yes I know it's not the same as the main intake MAF) with MAF cleaner. I looked at the little air filter assembly that the MAF attaches to, but it seemed pretty clean. This didn't help. With the engine off, I applied 12V to the secondary air pump and felt a lot of air coming out of the exhaust (which I believe proves that the air pump and valve are functional, and that the head is not clogged/blocked with carbon).

I removed the valve. I understand from searching this forum and others that some of the valves are vacuum-actuated and some are not. This valve has NO vacuum line, so there is no vacuum circuit diagnosis that needs to be done. I can blow through the valve both ways if I blow hard, which I believe is how these are supposed to work (the pressure from the secondary air pump opens the valve) and again, when I apply 12V to the fan, I get lots of air at the tailpipes. I'm a little confused on this point because the valve doesn't seem to be working like a check valve (ie if you blow hard from the engine side, you can still get air to go through).

After resetting the code, it comes back in a day or so.
I checked the hoses (from the little filter to the secondary air pump and from the pump to the valve); they are supple and have no cracks (and I would have heard whistling from the hoses when I got air out of the tailpipes, so I conclude that there are no leaks).
I replaced the secondary MAF with a new one. Still getting the codes.
I replaced the air pump (even though the one in the car appeared fine). Still getting the codes.

I pulled the relay that activates the air pump. I believe it is the salmon colored one in the e-box that's under the right side of the windshield. It is a normally open relay that tested infinite resistance normally (which is good) and 0.4 ohms when I apply 12V to the coil (which is good). I applied and removed 12v a few times to make sure the relay didn't stick. Relay seems perfect.

I replaced the valve mounted on the engine head. When I had it off, I sprayed a little brake cleaner in the hole; a small trickle of black gunk came out but I think that was just carbon residue coming off the walls of the channel, it was not fully blocked. The new valve 'tested' the same as the one that came off the car (I can get air through it if I blow hard).

Still getting the code.
What could possibly be causing these codes to keep coming back?

Is the valve operating correctly? Could the new one be bad as well? How does one test this? The info I find online seems to cover the vacuum-actuated ones, which is not what I have.

Thank you for reading all this!

80stech · #2 08-28-2025, 06:04 PM

It could be that you are using inferior parts, I went through that a while back! Maybe do a search of my posts if you are interested. Do you have any more info on exactly what the "split air" code is referring to ??

For sure there should be no exhaust going back through the air valve, that can ruin the air pump and the flow sensor.

ThreeGermans · #3 08-28-2025, 10:56 PM

Thanks 80stech!
I found your old post: https://xoutpost.com/bmw-sav-forums/...ump-drama.html

I too was wondering if perhaps the new parts I put in are no good. I am thinking about swapping back to the existing parts, since they seemed to work. I have two issues:

1) I still don't know how to check the (non vacuum actuated) valve

2) I have no way to force the pump on unless I clip 12V into the connector, but I can't force the car to turn the pump on, and I understand that it only goes on for 60-90 seconds if the car is cold, so it's impossible to repeatedly check the system in the summer...

X5chemist · #4 08-29-2025, 07:24 AM

What's the actual code? Mine had a secondary pump code. I knew it was failing because I could hear the bearings making noise. Two replacement pumps set the same pump code. A third replacement pump worked. The two lower priced air pumps didn't work. A Hella pump from RockAuto worked. RockAuto let me return the two other brands. Jumping the pump with 12V has full battery amps. Replacement pumps probably have higher motor start resistance. The higher resistance probably sets the codes. Try a Hella air pump. It worked on mine

ThreeGermans · #5 08-29-2025, 10:19 AM

Quote:

Originally Posted by X5chemist

What's the actual code? Mine had a secondary pump code. I knew it was failing because I could hear the bearings making noise. Two replacement pumps set the same pump code. A third replacement pump worked. The two lower priced air pumps didn't work. A Hella pump from RockAuto worked. RockAuto let me return the two other brands. Jumping the pump with 12V has full battery amps. Replacement pumps probably have higher motor start resistance. The higher resistance probably sets the codes. Try a Hella air pump. It worked on mine

Thanks! I will look into this.

I am getting two codes: P1419 (split air #2 circuit malfunction) and p0491 (secondary air injection system bank #1 malfunction- insufficient flow)

The pump I started with in the car appears to be good, but it is possible it is drawing too much current (?) It definitely runs and blows air. It is loud, but it was always loud (sounds like a jet engine taking off). I measured the current with a bench power supply, it was something like 26 amps at 13VDC. I didn't check the current draw of the replacement pump.

I will say that I stopped hearing that noise this summer, but I thought the car didn't run the secondary air pump when starting at higher ambient temperatures and so this was normal (?)

The new pump was from RockAuto, but I think it will be a hassle to return/exchange. It was a cheaper make: https://www.rockauto.com/en/moreinfo.php?pk=9722548

80stech · #6 08-29-2025, 10:12 AM

There is really is no way to be sure the check valve is good so it's best to replace it. The check valves only last so long and are a known issue. You can turn the pump on through INPA or a good scan tool.

ThreeGermans · #7 08-29-2025, 10:25 AM

Quote:

Originally Posted by 80stech

There is really is no way to be sure the check valve is good so it's best to replace it. The check valves only last so long and are a known issue. You can turn the pump on through INPA or a good scan tool.

I do keep running into situations where INPA is recommended. I know nothing about this; is there a good place to start learning?

X5chemist · #8 08-29-2025, 12:44 PM

I looked at my spreadsheet. I didn't write down the specific code. I do remember it saying insufficient flow. The pump was screeching when it was about to fail. It set the insufficient flow code. I tried the SKP and URO from RockAuto. Both were returned for a HELLA*728124190. $202.79 I don't see it offered on their website. The part number is now listed at PIERBURG.

I have a Foxwell 520 Pro with BMW software. I can activate all components on my X5. I like to use for fan activation and smog pump testing. It's good to test if switches or a motor have failed.

If you return the part, mention why. I stated the first two set insufficient air flow codes. I had no trouble returning them. Plus, I ordered the next expensive one.

80stech · #9 08-31-2025, 11:05 AM

I've recently been getting charged for shipping back to RockAuto when returning a faulty part so not at all worth it to even try the cheaper stuff any more. Just went through this again with a Vaico VANOS solenoid for the N52, total crap.

ThreeGermans · #10 10-04-2025, 10:21 PM

Just to follow up. I shouldn't have tried to change so many parts at once. Turns out spraying out the secondary MAF didn't work (even though it looked fine). I put in a new MAF sensor but when I added the aftermarket secondary smog pump it made things worse. I think I found an OEM Pierburg pump online for $200 but turns out I didn't need it. I removed the RockAuto pump and put back in the one that was in the car when I started and all the codes went away and stayed away (have 500+ miles on it now and no codes). Lesson learned. Thanks for the help.