Elusive P0174 code on '99 3.8l

'99 SEL 3.8l. Nearing 330K miles.

The engine light came on some days/miles before having it tested. P0174. Lean burn in bank #2. Normally I would assume a unmetered air intake into bank #2, but with the high mileage on the vehicle, I was a bit skeptical. The upper intake has had the green bolts installed for over 100k miles ... they probably are OK. When one attempted to shake it, the plastic intake seems very stiff ... no movement. I inspected and found no other obvious air leaks.

Because of the high mileage, other things may be at play. I swapped the primary oxygen sensors between the two banks. The battery was disconnected during this process. The van has since been driven over 500 miles ... NO ENGINE LIGHT!

Could unplugging/plugging the sensors improve some connection properties? Maybe. Or perhaps one of the sensors is just "hypersensitive". ???

Perhaps "time will tell" ... perhaps not.

Stay tuned!

I clicked on this thread before I read who posted it....and before it came up I thought "what am I going to tell him that he doesn't already know?"

You could well be right....improved connection.
Or something in your messing around corrected some vaccum leak.
Whatever the cause....if the light doesn't come back.....problem solved.
If it does, then you have eliminated a couple possible causes.....

The only value of the posting is to show others that taking a "second look" ... in this case, swapping the sensors and testing ... may sometimes be worth the effort.