Hello

I know this topic has been discussed in depth and there are so many possibilities, but I am looking for help with the little old P0171 code.

I recently purchased a 2015 Xc70 T5 with only 43k miles. It has only been driven like 5k miles in the past 3 years.

When I purchased it it was missing the gas cap. I don't know why. 😕 The check engine light was on. I figured ok the cel light had to be gas cap related as the car checked out great.I purchased an aftermarket gas cap. 3 days later the CEL turned off , awesome.


Yesterday it popped back on, EEEK. Just to cover all bases I should note the day before I did go through a car wash that blasted the underside.
I had the codes read today and they came in this order

1. P0171 "STORED" DTC SEVERERITY 2/3 system too lean
2.P0455 "STORED "evaporative system leak
3. P0171 "Pending" system too lean
4. P0171 "Permanent " system too lean

I'm pretty handy but not a diagnostician. Is that a word?

Everything I have read, it seems like there is no one single answer and it sounds like shops start throwing parts at it until they find the fix.
I can't afford to pay a shop to do that, so thought maybe I'd ask you all fine folks what cheap options I can start with myself.

I do not see nor hear any vacuum leaks. The Air filter is pretty dirty and I'm guessing original as all of the foam has disintegrated off the bottom. I ordered one and will replace this week. I'm having a hard time believing that could be the culprit though.

Only other thing to note,the car does have a burning smell. There are no oil leaks and it doesn't really smell like burning oil or rubber. I can't really describe it. I'm hoping it's just dirt, leaves dust burning from sitting so long.

Thanks for reading and any advice.