Secondary Air Pump Troubleshooting

jpregione · 08-08-2016, 10:20 AM

2009 328i, N51 engine, AA headers and tune with O2 delete. Got the registration renewal the other day and wouldn't you know it SES light comes on the next day, code thrown was for secondary air system flow low banks 1 and 2. Cleared the code and drove for a few days, after 5 days the light comes back and the same code appears.

I did some research and found a t/s page for the system but it was for the older vehicles, ones with vacuum control switch for the check valve. I pulled the check valve from the manifold and it appears to be working (blew on one side and had flow, blew on the other and it was restricted) and since the code isn't throwing every day my assumption is the pump is ok.

My issue is what is next? I only found one fuse and that was good, didn't find a relay for it in my chiltons manual so have no idea where to look for that.

Anybody have any suggestions on where to go next? 23 day until emissions is due

kkasson · 08-08-2016, 11:24 AM

The SAP is explicitly covered by the SULEV emissions warranty for 15 years/150,00 miles. The dealership should cover any diagnostics/repairs for it. However you might have an issue with that if your exhaust is modified.

The pump only runs on a cold start. Next cold start you could disconnect the hose from the pump and check if it's pumping air.

When the pump is running the car expects the values from the O2 sensors to go lean because of the extra air in the exhaust. If the pump is pumping air, then the only other possibility would be with the O2 sensors. If yours are deleted, I'm not sure what it does to compensate for that. If you didn't have a problem before then I'd guess the tune somehow accounts for it. So I'd start with making sure the pump actually works. It might take a couple days to set a code even if the pump isn't working.

jpregione · 08-08-2016, 02:10 PM

you bring up a good point about checking the pump for operation, i assumed that since it wasn't throwing a code on every cold start that the pump was working.

birdman19 · 08-17-2016, 04:06 PM

I had no other choice and dragged myself into the dealership. Found out that the relay for the pump was fried. They replaced and hopefully that is the fix.

m_thompson · 08-19-2016, 11:41 AM

Fixed under the SULEV emissions warranty?

08-08-2016, 10:20 AM	#1
jpregione Private 12 Rep 85 Posts Drives: 2009 E90 328i Join Date: Oct 2015 Location: San Tan Valley Arizona iTrader: (1)	Secondary Air Pump Troubleshooting 2009 328i, N51 engine, AA headers and tune with O2 delete. Got the registration renewal the other day and wouldn't you know it SES light comes on the next day, code thrown was for secondary air system flow low banks 1 and 2. Cleared the code and drove for a few days, after 5 days the light comes back and the same code appears. I did some research and found a t/s page for the system but it was for the older vehicles, ones with vacuum control switch for the check valve. I pulled the check valve from the manifold and it appears to be working (blew on one side and had flow, blew on the other and it was restricted) and since the code isn't throwing every day my assumption is the pump is ok. My issue is what is next? I only found one fuse and that was good, didn't find a relay for it in my chiltons manual so have no idea where to look for that. Anybody have any suggestions on where to go next? 23 day until emissions is due
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08-08-2016, 11:24 AM	#2
kkasson Lieutenant 187 Rep 589 Posts Drives: 07 BMW 328i, 08 BMW 528i Join Date: Jun 2015 Location: CA iTrader: (0)	The SAP is explicitly covered by the SULEV emissions warranty for 15 years/150,00 miles. The dealership should cover any diagnostics/repairs for it. However you might have an issue with that if your exhaust is modified. The pump only runs on a cold start. Next cold start you could disconnect the hose from the pump and check if it's pumping air. When the pump is running the car expects the values from the O2 sensors to go lean because of the extra air in the exhaust. If the pump is pumping air, then the only other possibility would be with the O2 sensors. If yours are deleted, I'm not sure what it does to compensate for that. If you didn't have a problem before then I'd guess the tune somehow accounts for it. So I'd start with making sure the pump actually works. It might take a couple days to set a code even if the pump isn't working.
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08-08-2016, 02:10 PM	#3
jpregione Private 12 Rep 85 Posts Drives: 2009 E90 328i Join Date: Oct 2015 Location: San Tan Valley Arizona iTrader: (1)	you bring up a good point about checking the pump for operation, i assumed that since it wasn't throwing a code on every cold start that the pump was working.
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08-17-2016, 04:06 PM	#4
birdman19 Registered 0 Rep 4 Posts Drives: 2009 BMW 328i X-Drive Join Date: May 2016 Location: Bronx, NY iTrader: (0)	SAP fix I had no other choice and dragged myself into the dealership. Found out that the relay for the pump was fried. They replaced and hopefully that is the fix.
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08-19-2016, 11:41 AM	#5
m_thompson Major 133 Rep 1,416 Posts Drives: M-Sport 128i, 328xi, 3.0CS Join Date: Jun 2008 Location: New England, USA iTrader: (0) Garage List 2009 128i [0.00] 1972 3.0CS [10.00]	Fixed under the SULEV emissions warranty? __________________ '09 128i - Black Sapphire Metallic\Coral Red\Glacier Silver\N51 DISA\6MT\Navigation\Premium\M-Sport\Heated seats\Xenon\Headlights\iPod\Smartphone\Euro Delivery
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