I keep getting a lean bank code. I have cleaned tb and replaced one of the rubber lines. It only comes on when I take a good ride with the truck. Not sure what else it could be. I'm thinking O2 sensor maybe.

2008 F-350 5.4 3V. 65k miles

Thanks
Matt

 

Yep, an oxygen sensor could cause that. Lots of other things can as well:

http://www.obd-codes.com/p0171

Has the fuel filter been changed? How does it run at idle? At WOT?

 

Fuel filter was changed a few months back. Idles great. A lot better since I cleaned the MAF and the TB. It's weird it only comes on when I take it out on the highway for a drive. I've been driving it for months around town for landscaping, no issues.

Matt

 

An 02 sensor is just that, a sensor. As mentioned, there are many causes, from Vacuum leaks, EGR, injector misfire, worn plugs (gap) exhaust leaks, cat-converter etc. Don't assume just a new sensor will repair the issue. With higher mileage vehicle replacing all of them can do a lot to increase fuel economy. Good luck ...

 

O2 sensors do NOT cause "lean" codes except very, very rarely. It's almost always something else. Usually a vacuum leak or a fuel delivery issue.

I would assume exactly the opposite.

Only if the sensors are "worn out" to the point they're no longer accurately or quickly measuring the exhaust mix correctly. Do not replace all of them as only the upstream sensors control fuel economy, the downstream ones just tell the computer how the converters are working.

 

I have an '09 5.4 F250 and was having some issues and it ended up being the catalytic converters.
Ford is replacing the Y pipe assembly and cats for free. Was an issue on the 3 valve engines.
Not saying this is your problem but mine was throwing lean codes and a shorted out O2 sensor. I cleaned my TB, MAF sensor and finally ended up taking it to the dealer. Sometimes it's worth going to the dealer.
I try to stay away as much as possible though.
Good luck and let us know what you find.

 

Both O2 sensors are new when the manifolds were done along with the cat. All from ford under extended wareentee

Idle is spot on perfect

Matt

 

Looking at fuel trim at idle and at 2500 rpm would provide some direction as to whether you have a vacuum/air intake problem or a fuel delivery/maf problem.

 

What device do I need to look at trims ?

Matt

 

a code reader that shows live data.