[chazzz]

My son has a 2008 BMW 328i and is registered in California. The SES light came on. I checked it with my OBD scanner and it showed that the error code is P0492 (Secondary Air Injection System Insufficient Flow Bank 2).

Looks like it needs a new Secondary Air Injection.

I am not sure if this car is covered by emission warranty. Also, I am not sure if this car is SULEV.

Will BMW dealer replace Secondary Air Injection at no charge? Is the car SULEV? I believe that the engine is N51.


Need your help and thanks!

[PhaseP]

Secondary air system only came with SULEV N51

[gbalthrop]

Originally Posted by chazzz

My son has a 2008 BMW 328i and is registered in California. The SES light came on. I checked it with my OBD scanner and it showed that the error code is P0492 (Secondary Air Injection System Insufficient Flow Bank 2). Looks like it needs a new Secondary Air Injection.
I am not sure if this car is covered by emission warranty. Also, I am not sure if this car is SULEV. Will BMW dealer replace Secondary Air Injection at no charge? Is the car SULEV? I believe that the engine is N51.

I believe the extended N51 SULEV warranty has been posted on one of the BMW forums, and it generally covers emissions-related components, but I would encourage you/your son to obtain/examine the warranty terms. Keep in mind it COULD be something as simple as a fuse, or air hose.

Here is a link to the TIS circuit diagram for the 2008 328i N51 Secondary Air System:
https://www.newtis.info/tisv2/a/en/e...system/vPDGiGd

I'll attach a screen print of Bentley Manual, p. 130-12, that explains the components of the system, to the next post so it doesn't ruin the margins of this one.

George

[gbalthrop]

Secondary Air Injection Function
Bentley, p. 130-12
As referenced in prior post

[tercero]

Originally Posted by gbalthrop

Secondary Air Injection Function
Bentley, p. 130-12
As referenced in prior post

Do you know the fuse number for the secondary air pump ?
2007 328i convertible

Thanks

[gbalthrop]

Originally Posted by tercero

Do you know the fuse number for the secondary air pump ? 2007 328i convertible Thanks

It depends. Please provide Last-7 Characters of VIN so we can ensure correct circuits. Many wiring changes 3/1/2007
in middle of 2007 model run.

If 2007B, built AFTER 3/1/2007, Fuses F75 & F70, power Relay K6304, located on JB Fuse Panel.

If 2007A, built BEFORE 3/1/2007, Fuse F06 in E-Box & F68 on JB Fuse Panel. Relay is same, as well as X1124 Connector.
See attached ISTA ScreenPrints. If questions on HOW to test, please indicate Make/Model of Scan Tool, Software.
George

[tercero]

VIN P150023
2007 328i convert

Do you know the reason why the secondary pump just runs for less than 20 second cold start?

I checked everything else but I can’t find the fuse inside the glove box
I am afraid it maybe carbon build up inside the car.

What’s your take ?

Thank you.

[tercero]

Does any body knows how long does the secondary air pump should run at a cold star ?
My is only running for 10 seconds is this normal ?
My check engine light keeps coming back on
Pump works
Valve works
Cleaned the area where the valve goes

Any suggestions ?

[autoAER]

Subbed for info since my E93 N51 is having the same exact issue.

This is where I’m at in the diagnosis:

1. I tested that the pump works via INPA activation. Pump kicks on and air flows out both exhaust tips.

2. The check valve is patent with no retrograde air flow. The hoses connecting the air pump to the valve appear to be patent without cracks or visible issues

3. Scrubbed away the carbon dust from the port with chemo b12, does not appear to have any issues and there is air flow from both sides of the port when engine is turned on

4. Ran complete diagnostics on INPA - green across the board, including lambda sensors. The only code present is 2A00 insufficient air injection bank 2.

Now, as I understand it, the secondary air injection system injects air into the cylinders in order to help warm up the catalytic converters faster for reduced emissions on cold starts. Seeing as it appears that there is adequate flow through the system when the engine is OFF (test 1 above), I am leaning towards a vacuum leak as being the source of this issue. I will update as I go along in the event I figure it out. I’m currently losing my mind chasing it down as I cannot renew registration for the car in California since it will not pass smog inspection due to the SES light being on

[autoAER]

Just wanted to update you guys in case this information proves useful

I ended up buying another check valve and air pump for cheap for a little procedure I came up with after doing some research.

Essentially, I filled the second air pump I bought with B12 chemtool and attached it to the check valve after blocking one side of the exhuast port where the check valve attaches. In my case, the code was for bank 2 so I blocked off the right port. I then reassembled everything with the port still blocked off, and let the pump run via activation through INPA (do NOT turn the engine on, just let the pump run multiple times)

I refilled the pump several more times throughout the course of 5 hours or so, letting the pump run then allowing some time for the B12 to evaporate.

After letting it sit for about 6-8 hours, I then filled the pump one last time and this time I started the engine

Smoked like crazy for about 30 minutes, then I took it for a lengthy high RPM drive through the back roads.

Car now starts smoothly with no more rough idle, and power is available on demand

SES light is currently off as I reset it through INPA. I will update thread once I confirm the code is actually gone (in about 100 miles or so of driving)

Another member on the forum suggested cutting the top off of a spare check valve and using it to push B12 through the system - this is what I’ll likely do next if the problem isn’t solved

[autoAER]

Just a quick update - I did a deeper dive into the motor as it wasn’t making sense that the secondary air injection could be clogged.

I found 4 loose bolts and a puddle of oil on the exhaust headers, near the bottom of the valve cover, presumably incorrectly done by the last person who replaced the valve cover gasket. I removed the valve cover entirely, inspected, reassembled and torqued everything to specification. I will update if the SES light comes on again - I suspect most of the reasons that cause the “insufficient air flow” or “secondary air injection” codes are caused by issues with the various vacuum hoses or the valve cover itself. I promise you mechanics rarely check for the actual cause and even if they do they will tell you the worst case scenario to try and get you to pay big, which in this case is removing the head and cleaning the ports from inside, major $$$$ so definitely check these before shelling out.