Bank 1 running lean
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New User
Joined: Sep 2007
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Bank 1 running lean
The service engine light is on and the code says that the heated o2 sensor is not working and that it is running lean on bank 1. I have replaced the o2 sensor and it still is throwing the code. Any tips?
PS. It gets horrible gas mileage.....about 9mpg.
PS. It gets horrible gas mileage.....about 9mpg.
Cargo Master
Joined: Apr 2003
Posts: 3,476
Likes: 224
From: Frequently frozen MN
I'm far from an expert, but there may really be a lean condition in bank1
- leak in intake manifold
- clogged or dirty injector(s)
- other stuff that the smart folks here know about
As for the O2 sensor, is the code telling you about a bad sensor or a bad heater?
In any case, it could be a wiring problem. O2 sensors are supposed to read around 0.9 v, but it's supposed to switch as the computer adjusts the mixture . I don't know what voltage should be on the heater (probably 12v).
One thing that might explain both issues us a crack in the exhaust manifold.
This could make the O2 sensor read out of range lean. Depending on what
the value is, it could also report as a lean bank.
fordfuelinjection.com has a lot of info on how the systems work.
Good luck,
ford2go
- leak in intake manifold
- clogged or dirty injector(s)
- other stuff that the smart folks here know about
As for the O2 sensor, is the code telling you about a bad sensor or a bad heater?
In any case, it could be a wiring problem. O2 sensors are supposed to read around 0.9 v, but it's supposed to switch as the computer adjusts the mixture . I don't know what voltage should be on the heater (probably 12v).
One thing that might explain both issues us a crack in the exhaust manifold.
This could make the O2 sensor read out of range lean. Depending on what
the value is, it could also report as a lean bank.
fordfuelinjection.com has a lot of info on how the systems work.
Good luck,
ford2go
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
"Lean" codes
"Lean" codes do NOT mean the engine is running lean, it usually means it's running RICH. That's why your fuel economy has gone down.
Lean codes indicate the computer has maxed out the fuel trim (excessive fuel) but the O2 sensor still shows the exhaust is still leaner than it should be.
Almost ALWAYS caused by an intake leak or an exhaust manifold leak - anything that allows unmetered air in before combustion or exhaust out before measurement.
Lean codes are almost NEVER due to faulty O2 sensors.
Lean codes on both banks are usually due to a vacumm leak in the intake tract common to both banks or a dirty/faulty MAF sensor. The PCV hose elbow is, by far, the most common reason.
Always post the exact DTC, not just descriptions. SEARCHing for the DTC code(s) will usually find previous discussions that will answer your question before you even ask the members.
Steve
Lean codes indicate the computer has maxed out the fuel trim (excessive fuel) but the O2 sensor still shows the exhaust is still leaner than it should be.
Almost ALWAYS caused by an intake leak or an exhaust manifold leak - anything that allows unmetered air in before combustion or exhaust out before measurement.
Lean codes are almost NEVER due to faulty O2 sensors.
Lean codes on both banks are usually due to a vacumm leak in the intake tract common to both banks or a dirty/faulty MAF sensor. The PCV hose elbow is, by far, the most common reason.
Always post the exact DTC, not just descriptions. SEARCHing for the DTC code(s) will usually find previous discussions that will answer your question before you even ask the members.
Steve
Senior User
Joined: Aug 2007
Posts: 203
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I was running lean in both banks myself and was also getting terrible mileage. ALso changed all my O2 sensors. It was indeed a vacumm leak in my intake. Like some other fellas here suggested take an unlit plumbers torch to the intake with the truck on, if there's leak, you will hear the engine rev up a bit. Also, clean the MAF sensor
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