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Random Bank 1,2 lean codes

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Random Bank 1,2 lean codes

Postby bobbabouie91 [OP] » May 22 2011, 5:08am

My truck runs great, except every once in a while my check engine light comes on and reads that both bank 1 and 2 are running too lean. But throws no other codes. Usually the code goes away on its own. But I've noticed sometimes, Very rarely, when I go to take off it will hesitate. I've checked th o2 sensors and theyre fine, cleaned the MAF sensor. Could this possibly result from a clogged fuel filter? It's my only guess, cuz it has been probably 10-15,000 miles since I've changed it
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Re: Random Bank 1,2 lean codes

Postby gmctruckguy » May 25 2011, 3:59am

How long has it been doing this? Maybe bad fuel? Do you have any mods on it?
10638His & Hers 2012 Sierra C/C's 6.2L, 4WD, 3.73's, Airaid CAI, Diablo Predator/inTune, Magnaflow Exhaust, Piaa's, 3 1/2" RC Lift, 285 BFG T/A's, Bushwacker Flares, Tuff Country Add-a-Leaf
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Re: Random Bank 1,2 lean codes

Postby bobbabouie91 [OP] » May 25 2011, 4:17am

Ive only noticed it for maybe the last 5000 miles. The only mods are cai and exhaust. Otherwise bone stock
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Re: Random Bank 1,2 lean codes

Postby gmctruckguy » May 25 2011, 4:21am

Well those mods could possibly kick out those codes. Check for air leaks in your CAI, tighten up all the hose clamps and check for exhaust leaks anywhere.
10638His & Hers 2012 Sierra C/C's 6.2L, 4WD, 3.73's, Airaid CAI, Diablo Predator/inTune, Magnaflow Exhaust, Piaa's, 3 1/2" RC Lift, 285 BFG T/A's, Bushwacker Flares, Tuff Country Add-a-Leaf
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Re: Random Bank 1,2 lean codes

Postby bobbabouie91 [OP] » May 25 2011, 4:46am

I do have a slight exhaust leak coming from the manifold, why would that make the computer lean my system?
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Re: Random Bank 1,2 lean codes

Postby gmctruckguy » May 25 2011, 4:48am

Because your getting air into your exhaust and then your O2 sensors are picking it up and thinking your exhaust is lean, ie has to much air compared to fuel in it.
10638His & Hers 2012 Sierra C/C's 6.2L, 4WD, 3.73's, Airaid CAI, Diablo Predator/inTune, Magnaflow Exhaust, Piaa's, 3 1/2" RC Lift, 285 BFG T/A's, Bushwacker Flares, Tuff Country Add-a-Leaf
1063910640

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Re: Random Bank 1,2 lean codes

Postby bobbabouie91 [OP] » May 25 2011, 12:50pm

I would think that would cause the system to add more fuel to compensate, therefore throwing a too rich code, I'm not sure though. Im no expert
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Firing on 4 cylinders [L1]
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Re: Random Bank 1,2 lean codes

Postby gmctruckguy » May 25 2011, 2:43pm

You would THINK thats what it would do but you still have other sensors on the engine, ie. MAF, IAT, MAP, that is measuring air coming in, telling the computer how much fuel to mix to keep it at stoichiometric (14.7/1) the O2 sensors are reading what is coming out of the compustion chamber (or in this case oxygen leaking into the exhaust) it will compensate to an extent but its reading what is down stream, whether its lean or rich.
10638His & Hers 2012 Sierra C/C's 6.2L, 4WD, 3.73's, Airaid CAI, Diablo Predator/inTune, Magnaflow Exhaust, Piaa's, 3 1/2" RC Lift, 285 BFG T/A's, Bushwacker Flares, Tuff Country Add-a-Leaf
1063910640

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