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Now: 2008 STS-V, 1960 Eldorado Brougham Then: 2002 Escalade
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Discussion Starter #1
P0174 Fuel Trim System Lean Bank 2

Been getting a PO174 on and off for a few weeks, sometimes with a couple hundred miles in between.

I'm going to change the air filter, but was wondering if anyone had the GM part numbers for the front O2 sensor and MAF in case I need to get those too. I'm off warranty and want to avoid a trip to the dealership if I can.

Oh, and is Bank 2 the left or right?
 

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2006 STS-V and 2007 STS-V The Murdalac
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Bank 2 is left (driver's side)

Check for leaks in the ducting between the air filter and the throttle body. That would be my guess.
 

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Now: 2008 STS-V, 1960 Eldorado Brougham Then: 2002 Escalade
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Discussion Starter #3
Thanks. I'm going to replace the filter tomorrow and check for leaks. It shouldn't be rainy tomorrow.
 

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2007 STS-V
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193 Posts
Agreed with TimmyC. This is a leak. Getting extra air in somewhere causing ECU to increase fuel trim. Same code on a 98 lincoln years ago. Leak in the vac
line due to a cracked plastic T connector hidden under a cover. Hard to find as it comes and goes.
 

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'06 STS-V, '17 CTS-V
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Just got this code yesterday. Finally hit 80 degrees here around the PHL/NYC area, and when the car got up to temp, the code popped. Figured it was the expansion/contraction of the boot on the TimmyC intake to the pipe, as I installed it in 40 degree weather. Reinstalled it, tightened everything up, touched the positive cable to the black terminal to clear the codes, and success, no code when I re-ran the absolute SH!T out of it. Funny though, how it comes up lean bank 2. Why wouldn't Bank 1 scream lean as well?
 
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