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madmike
03-26-2009, 05:13 AM
Hello all. I just pulled my trouble codes from my 03 H2.

P0171 System to lean bank 1
P0174 System to lean bank 4

I will be doing more diagnostics today but is there a quick fix to these? A cronic problem others have had with these codes and first place to look?

Manual advises
the system will go lean if injector is not supplying enough fuel.
A lean condition could present during high fuel demand.
Posted this in another forum. Wondering if any techs in here:)

Any ideas? thanks in advance

IRA51
03-26-2009, 10:01 PM
change your fuel filter ,add a can of Seafoam to a full tank of gas ,drive it like you stole it . :)if that doe's not solve it check your fuel pressure ,if it is low you will need a new fuel pump .

HUMTECH
03-27-2009, 05:25 AM
How many miles on the truck? What year? Sounds to me like the intake gaskets are leaking. The 6.0l uses a dry intake(no coolant flow through) and when the gaskets start to leak it is a vacuum leak. Un-metered air into the combustion chamber causes the truck to run lean. Best way to check it is have a scan tool hooked up and run the engine at a cold start up and monitor the fuel trim short term percentages and spray intake(carb) cleaner where the intake and cylinder heads meet and if the percentages change abrubtly your intake gaskets are leaking. When it gets real bad you can notice a rough idle and even miss fires when cold starting.

HUMTECH
03-27-2009, 05:31 AM
BTW P0174-lean bank 2, not 4. Bank 1 is the left side, bank 2 the right side.

madmike
03-30-2009, 07:27 AM
You are correct. Bank 1 and 2 :D . I changed out the filter and am adding injsector cleaner at every fillup. So far code hasnt returned. As a previous poster said , it was stumbling at start up for a bit. Havent had that problem either. Great idea spraing carb cleaner when running and watching the values on the code reader. Although I think I solved the problem. Been about a week and no engine light yet. Thanks folks.