O2 sensor causing lean code ?
Thread Starter
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Fleet Mechanic
Joined: Mar 2006
Posts: 1,519
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O2 sensor causing lean code ?
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
2008 F-350 5.4 3V. 65k miles
Thanks
Matt
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
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?
http://www.obd-codes.com/p0171
Has the fuel filter been changed? How does it run at idle? At WOT?
Thread Starter
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Fleet Mechanic
Joined: Mar 2006
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Likes: 134
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
Matt
Elder User
Joined: Jun 2014
Posts: 932
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From: Tampa
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 ...
Hotshot
Joined: Jan 2004
Posts: 19,763
Likes: 1,081
From: St Louis
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.
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.
Freshman User
Joined: Dec 2009
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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.
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.
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Fleet Mechanic
Joined: Mar 2006
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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
Idle is spot on perfect
Matt
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Elder User
Joined: Jan 2002
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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.
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