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      11-14-2021, 07:02 PM   #1
Jkan
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SAP 27AF error but confirmed pump working

Hi everyone, I've been banging my head against my cylinder wall trying to pinpoint the cause of this error code. Was hoping someone might have an idea or if anyone has successfully solved this issue can chime in. Thank you so much in advance.

I’ve been getting a 27AF - P1411 (and occasionally 2B59) code since the temperature dropped (not sure if it coincidence or what) during cold start and will stay on till I clear. Once clear it’ll not come back on for a few cold start. I’ve done a lot of research into it (including this forum and Facebook groups) already 😰

I have followed the “action in service” for the 27AF error code by:

1. Check wiring to secondary air pump
2. Check plugs and wiring harness on secondary air pump
3. If OK, remove secondary air pump relay, and connect the two terminals (30 and 87) in the socket with ignition on, if secondary air pump still does not start, it is defective, replace secondary air pump.

SAP is functioning when I bypassed the relay In step 3. The pump pushes air out with no issue. I also bench tested the relay and it’s functioning.

I was not able to fin the complete “4th step” instruction online anywhere.

Additionally:
-I checked fuse 89 in glove compartment
-battery is new (2 months)
-alternator voltage seems fine.
-air flow sensor on the suction tube into the pump seems to be producing a reading based on BimmerLink sensor data

The valves are notoriously difficult to reach, so I don’t even see a way to check the valves condition…

Anyone have suggestions on how to test the valves without removing it?
Is it possible the Pre cat o2 sensors are bad and thus giving bad readings (but I would presume a different code would’ve been thrown..?)

Would prefer not going the tuning route.

Thanks in advanced for any ideas

Last edited by Jkan; 11-14-2021 at 07:08 PM..
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      11-21-2021, 06:19 PM   #2
arucano
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I don't have an e92 but is there a vacuum hose running to the valve? On other BMWs the vacuum hose fails as it ages and prevents the vacuum from opening the valve. If there is a leak in that line there will be less vacuum to open the valve. If the valve is fouling/coking up, it may work when hot but not when cold. If there is no vacuum line to the valve, then the design is probably a "check valve" that opens on the pressure of the pump. In that case, the check might be sticking closed. You can try spraynig carb cleaner or something similar into the line from the pump to the valve and going through a few cold starts and see it that helps to free up the valve.
Also see the other post where the pre-cat O2 sensor was the cause.
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Last edited by arucano; 11-21-2021 at 06:33 PM..
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      11-29-2021, 01:15 PM   #3
Jkan
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Quote:
Originally Posted by arucano View Post
I don't have an e92 but is there a vacuum hose running to the valve? On other BMWs the vacuum hose fails as it ages and prevents the vacuum from opening the valve. If there is a leak in that line there will be less vacuum to open the valve. If the valve is fouling/coking up, it may work when hot but not when cold. If there is no vacuum line to the valve, then the design is probably a "check valve" that opens on the pressure of the pump. In that case, the check might be sticking closed. You can try spraynig carb cleaner or something similar into the line from the pump to the valve and going through a few cold starts and see it that helps to free up the valve.
Also see the other post where the pre-cat O2 sensor was the cause.
Hey, thank you so much!

I believe it's just 1 tube going from SAP to the valve, and then valve into the block. I presume it's a check valve.

The cold start does seem to work.

I have dumped seafoam into the tubes leading to the valves, and its been coming out of the exhaust as well. So I presume that means the valves are either stuck open working properly?

I also did replace the upstream o2 but still have that code.

Very strange/mysterious issue...

Thanks again!
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