My B7 S4 has started to throw a P0171 for bank 1 too lean. Couldn’t find anything on here via search and using Google I mainly found A4 stuff, just one guy with an S4 saying MAF. Figure this is the best site for actual technical knowledge on these cars… Would MAF only end up throwing codes on one bank?
Also should note, I’m running piggies from JHM and I’ve done the fuel filter and PCV valve in 9 months or so.
You are in the right place for help. Do you have a vag-com or just a code reader. A lean code can be from lots of things. If you have a vag-com I can help you find out what it is more quickly
Yea u gonna need a vag com man:)i got that code too a while ago and it was a mix of maf and 02 sensor!
That code tends to be from a vacuum leak. It is not unusual to only see that code for one bank but if you were to go into the measuring value blocks then I am willing to be that the other bank is probably seeing the same issue but it isn’t bad enough yet to throw a code for both sides.
Check that the 5 mm allen bolts that hold the intake manifold on are tight.
Look for old damaged vacuum lines.
Inspect the suction jet pump and lines that go to it.
Make sure that the MAF boot is on fully. Especially on the throttle body side.
Thanks guys, I’ll try to run through this list over the long weekend. Though someone’s got to point me to where the suction jet pump is, I have no idea.
And no, I don’t have vag com sadly, just using Torque on my phone to read stuff. I may be able to read out the right PIDs using it, but I’d have to know what they were. The tool is versatile enough that I was able to use it for some OBD in use monitoring ratio data gathering for CARB at my job a couple of months ago.