Obd2 code P0171 and P0174

[Dave_B]

I personally had the same codes. For me it was the DISA O-Ring. Fel Pro makes a gasket that works. Just search for the DISA O-ring thread in this section or a thread created by me about a month or so ago for the same 171 and 174 codes.

These guys are right. It can be...

DISA O-ring
Either intake boot
F connector
CCV lines
VCG
Bad MAF
O2's

The only way to really test if it's MAF or O2 is a scanner that can read live data.

You can smoke test the car too, to determine the location of the vacuum leak. There are several DIY's for this as well.

With the rough idle, I'm going to guess vacuum leak.

[jreyes19]

I personally had the same codes. For me it was the DISA O-Ring. Fel Pro makes a gasket that works. Just search for the DISA O-ring thread in this section or a thread created by me about a month or so ago for the same 171 and 174 codes.

These guys are right. It can be...

DISA O-ring
Either intake boot
F connector
CCV lines
VCG
Bad MAF
O2's

The only way to really test if it's MAF or O2 is a scanner that can read live data.

You can smoke test the car too, to determine the location of the vacuum leak. There are several DIY's for this as well.

With the rough idle, I'm going to guess vacuum leak.

I did the DISA O-ring and posted my own DIY video a week or two ago here lol
I did the Upper intake boot, the lower looks fibe

F connector?

also how do i check whether i have a bad MAF or O2 with live data, because my phone connects to the car and shows me all kinds of live data

thank you for your response it is very helpful

[Dave_B]

Yep, that's the thread I posted the FelPro PN in.

F connector is the plastic piece that goes into the upper intake boot. When separated from the intake boot, and the 2 lines it look like a capital F.

As for the live data, I'm going to clarify with my brother, the Bimmer tech. He mentioned it to me and explained it when I was diagnosing mine but I can't remember of the top of my head.

[jreyes19]

Ok thanks I will be double checking the f connector because I believe it is fine but never hurts to be sure lol

Please let me know about the live data I may be able to do it

Sent from my SAMSUNG-SGH-I997 using Tapatalk

[Dave_B]

Well, he couldn't tell me much other than "I just look at them and go from there" LOL.

I'm assuming he's looking at numbers pre and post cat on the O2's and not sure what he's looking at on the MAF.

Sorry I couldn't be of much more help.