The check engine light comes on and the cruise control light blinks and quits working. 
Computer reader says code 171, running lean. After it's reset, it does
it again when I'm on the road.  The interval had become short, and I'm
worried about TO WHAT the sensor is responding. Recently replaced an O2
sensor, but a week later it happened again, just driving around town. 
It's hot, but that's no excuse, is it? 

I'd sure like for this to be fixed, and hope you people have some ideas.

Why doesn't it correct the air/fuel mixture? Then maybe the sensor would stop complaining.

Edited September 11, 20169 yr by SunnyGardener

It doesen't because it cant. If you look at live data, you will still see it's adding tons of fuel into the short and long fuel trims, but it can't get the mixture where it wants. So it throws PO171 bank 1 lean..

 

On an N/A car, 99.99% of the time it points to a vac leak somewhere. The other .1 possibility is that your car has a MAF sensor which is not reading correctly

car details?

 

also, you can get a vacuum gauge on 'loan' from most any parts store.

Edited September 12, 20169 yr by 1 Lucky Texan

It's a 2007 outback.

Subaru Nut, thanks for your reply.  What is N/A?

Subaru Nut, thanks for your reply.  What is N/A?

Naturally Aspirated