01 Volkswagen Passat 1.8

Car came in today with a lean code P0171 and a incorrect purge flow code. In OBD generic, only the P0171 appears. Freeze frame of the P0171 makes no sense as it indicates the car was running slightly rich. I suspected a intermittent sticking open purge valve (evap) but I manually operated many times and it never stuck. Driving on a road test the car never ran lean, and as pictured the O2 didn't really switch quickly, not sure if the scanner just poorly shows the switching. Also strange I made a vacuum leak myself and while the short term quickly corrected rich, the long term never changed from 2.3. at all after 5 minutes of vacuum, or all the other testing or test drives. New to the page and loving it. Just looking for opinions, what I'm missing

Just wanted to say the first 3 are freeze frame. Last 2 are driving

It looks like a stuck pre-cat O2 sensor to me, With the engine at idle and in closed loop even the cheapest scantool should show the pre-cat O2 sensor going between about 0.1v and 0.8v about once per second. When fully warm a narrrow band O2 sensor will will "switch" suddenly between rich 0.8v and lean 0.1v .

Short term fuel trim and and pre-cat O2 sensor output mirror each other if the upstream O2 sensor is stuck or just lazy or out of spec the fuel trim will mirror it.. The Long Term fuel trim will only change when the average of the short term fuel trim changes.






What I would do i is look at the the pre-cat and post-cat O2 sensor voltages, at normal idle and with forced lean (vacuum leak) and forced rich (propane or brake clean in the intake.

Tried a sensor and it remained the same. I'm not sure that the data is correct. Under Volkswagen specific data, there's like 14 different readings for osb1s1. On generic obd there isn't one and the fuel trims aren't extremely lean, just a little rich. I feel like I'm missing something in the interpretation of Volkswagen data

The fuel trims aren't extreme the rule of thumb is
SFT1(rough average) + LTF1 is within + or - 10% is acceptable.

It really looks to me that B1S1 isn't producing the goods --- check the heater circuit and associated wiring. O2 sensor output should be available under OBD2 --- I always trust OBD2 data more than manufacturers.

I've seen a lot of perished hoses on VW's - they don't seem to be able to make rubber hoses that last. I always smoke test them first.
(apart from the possible O2 sensor fault you need to sort out)