increased emission - 27C5 and 2739 codes

Hi guys, I hope someone can help me with this issue.

I have increased emission / engine service soon warning on. I had someone check the fault codes and I got 27C5 and 2739

description for 2739 says "AIR MASS SENSOR SECONDARY AIR ELECTRICAL DIAGNOSIS"

description for 27C5 says "AIR MASS SENSOR SECONDARY AIR SIGNAL"

It looks like this sensor could be a problem. Has anyone had this type of issue and had it successful fixed? and would you have a part number and diagram for this sensor?

I really appreciate any feedback on this. I tried searching the forum but couldn't find any topics on these codes.

My emission testing is due this month. Great timing

bump. any feedback is greatly appreciated.

weird, the car doesn't have a MAF..

http://bmwclubuae.com/forum/showthread.php?6264-E92-Mass-Air-Flow-(MAF)-sensor-or-Alpha-N

I would email Mike Benvo and see what he suggests. http://www.bpmsport.com/

For anyone who searches these error codes on M3post, I had both of these codes at the same time. I replaced the air pump suction hose (with included sensor) BMW part #11727838504 and both codes have gone away permanently. BMW doesn't sell the sensor separately, but it is available with aftermarket brands if you think it is the sensor and find no damage/cracks in the hose. Careful about buying this part used. I did that at first on Ebay, but the item was poorly packaged (maybe damaged when shipped in a soft sided envelope) and didn't work (or maybe it was already defective before shipping). I would recommend purchasing this part new.

Link to website I borrowed the image from:

Any advice on how to replace the hose? I can't get behind the intake manifold and it seems it's bonded in place. Thx!

leo95se wrote

Any advice on how to replace the hose? I can't get behind the intake manifold and it seems it's bonded in place. Thx!

Check out the links in "Step 1" of this DIY to learn how the plenum (aka intake manifold) on this car comes off. It's still a pain to reach back there, but removing the plenum makes it much easier.

Genius! Thanks a ton, really impressive detail by all

Hey I wanted to see if yah can help so these codes keep popping up (2739 - 27C5) on I change the Air Suction Pump Hose already & my engine malfunction light still comes on, any idea what it can be

I look up the codes & it says


description for 2739 says "AIR MASS SENSOR SECONDARY AIR ELECTRICAL DIAGNOSIS"
Secondary Air Injection System Air Flow/Pressure Sensor Circuit High (Bank 1)


description for 27C5 says "AIR MASS SENSOR SECONDARY AIR SIGNAL"
Secondary Air Injection System Air Flow/Pressure Sensor Circuit (Bank 1)

Ralphy_Banks wrote

Hey I wanted to see if yah can help so these codes keep popping up (2739 - 27C5) on I change the Air Suction Pump Hose already & my engine malfunction light still comes on, any idea what it can be

I look up the codes & it says


description for 2739 says "AIR MASS SENSOR SECONDARY AIR ELECTRICAL DIAGNOSIS"
Secondary Air Injection System Air Flow/Pressure Sensor Circuit High (Bank 1)


description for 27C5 says "AIR MASS SENSOR SECONDARY AIR SIGNAL"
Secondary Air Injection System Air Flow/Pressure Sensor Circuit (Bank 1)

Did you manage to figure out the issue?

Shaun Ryan wrote

Did you manage to figure out the issue?

I went through this over the summer, take a look at the following thread - https://www.m3post.com/forums/showpost.php?p=25278193&postcount=15

BH_Fanaticos77 wrote

Hi guys, I hope someone can help me with this issue.

I have increased emission / engine service soon warning on. I had someone check the fault codes and I got 27C5 and 2739

description for 2739 says "AIR MASS SENSOR SECONDARY AIR ELECTRICAL DIAGNOSIS"

description for 27C5 says "AIR MASS SENSOR SECONDARY AIR SIGNAL"

It looks like this sensor could be a problem. Has anyone had this type of issue and had it successful fixed? and would you have a part number and diagram for this sensor?

I really appreciate any feedback on this. I tried searching the forum but couldn't find any topics on these codes.

My emission testing is due this month. Great timing

Code that shit out and straight pipe the machine.

I also had the secondary air hose replaced while my engine was out. Had code 2739 as well. Seems to have not returned for now..!

I wanted to thank Theodore for this solution posted. In my case mine was unplugged and this article lead me to find that, plug it back in and get back to no codes. With it unplugged I got three codes 279D Power Management close circuit current violation (not sure this is caused by the hose unplugged because car sat during the stay home order), 2739 Secundary air mini-hfm electr. Diagnostics, and 27C5 Secundary air mini hfm plausibility. I could not pass smog until I figured this out so it was great to not have to spend a ton of time messing with this.

Theodore wrote

For anyone who searches these error codes on M3post, I had both of these codes at the same time. I replaced the air pump suction hose (with included sensor) BMW part #11727838504 and both codes have gone away permanently. BMW doesn't sell the sensor separately, but it is available with aftermarket brands if you think it is the sensor and find no damage/cracks in the hose. Careful about buying this part used. I did that at first on Ebay, but the item was poorly packaged (maybe damaged when shipped in a soft sided envelope) and didn't work (or maybe it was already defective before shipping). I would recommend purchasing this part new.

Link to website I borrowed the image from:

Hi, did you have any rough running before you changed the hose?
I've got the codes, but don't want to replace unless likely to fix the hesitation I'm having when hot at very low revs when accelerating.
Cheers, Steve

kyrix1st wrote

Code that shit out and straight pipe the machine.

How do you code it out? I have protool and my tuner even said he can’t do it.

Found this thread as my car had the same 2739 27c5 codes. For anyone doing this in the future, you can buy just the secondary air MAF sensor (mini HFM sensor) by itself for $65 even though BMW only sells the entire 11727838504 hose + sensor assembly for $220. FCP euro or Amazon offer the Continental part, which is just the BMW part with the BMW logo ground off.

BMW sensor only part number (used on equivalent generation M5/M6): 11721438814
Siemens VDO / Continental sensor part number: 5WK9639Z

To perform the replacement:
1) Remove the intake plenum for access to the back of the SAP pump. I loosed the SAP pump mounting (but didn't remove it) to get better access to the hose release clip on the back side.

2) Mark the hose assembly with a line (silver sharpie in my pic) so that the new sensor will be correctly oriented towards the wire harness when you reattach. Remove the hose assembly and remove the two attached hoses - one attaches via T15 torx and the other is a hose clamp that I replaced with a worm drive clamp (or you can re-use if you have the oetiker clamp tool).

3) Reattach new sensor to old hoses, aligning the sharpie marks.