BMW Fault Codes – P0411, P0171, P0174, Secondary Air and Lean Mixture
This answer is applicable for many BMWs in addition to the one listed below.
car year: 2006
car model: X3 3.0i
Hi, quick question… I got the OBD-II error msg P0171, P0174, P0411 on my X3. The check engine light is on and the idle is rough. What part do I need to change?
The P0411 code is: Secondary Air System – Low Flow
This is saying that the air flow from the secondary air injection system is lower than what it should be. This could be due to a failing pump, check valve, Mass Air Flow sensor (MAF – specifically for the secondary air system), clogged ports in the cylinder head (becoming a common issue, unfortunately) and other system control issues. Further diagnosis will be required to determine if the pump and the rest of the system are working properly. If they are, you may have clogged ports. If faults are found, we can replace the faulty parts or assemblies. See the link below for more info:
The P0171 and P0174 codes are for lean mixture on bank-1 and bank-2 (all cylinders) and have been covered in prior blog posts: