Check Engine Light

[19652plus2]

Hey Guys, My '06 GTO(all stock) has a check engine light. My friend used his OBD and said the car has a PO171 and a PO174(lean bank). Anything I should be concerned about? This has happened before and cleared up by itself two other times.THANKS, Peter

[GTO JUDGE]

Well, I know PO172, and PO175 are Oxygen Sensor codes So I would think the codes you are getting may have something to do with the PCM readings and air mixtures. Have you installed a CAI, or had the MAS apart at all? Maybe the O2 sensors are indicating too much air is getting past the mass air sensor causing too lean a fuel mixture. Maybe cleaning the MAF with a brake, or electronic cleaner will fix it?

Maybe a dirty fuel filter?

Will it hurt anything? If the fuel mixture is not right, you'll notice reduced fuel efficiency and maybe rough running. Carbon build up with fouled plugs?

[19652plus2]

Hi, Thanks for the reply. The car is completely stock and nothing was ever taken apart. It does feel "rougher" and the fuel consumption is definitely greater when I look at the computer. Peter

[Verdoro 68]

I believe those are knock sensor codes. My car threw them after a rodent ate through my wiring harness. It seems odd that you would throw them with no mods to the car. Take a look under the hood and make sure the harness is intact (rear of the intake manifold, wires run under the intake manifold to the sensors in the valley) and all the hoses are connected.

Based on your symptoms (running rough, bad milage) I bet there's a vacuum hose that has either worn through or came off. If you don't see anything out of the ordinary under the hood bring it by the dealer and let them have a look.

[Larry P]

P0171 is fuel system lean in bank 1 (the drivers side of the engine) The bank 1, pos 1, HO2s (the o2 in the manifold) is telling the pcm that there is not enough fuel on that side of the engine. This o2 has been a problem for the 5.3 and 6.0 engines, most likely on a scanner it would show not much if any movement compared to the bank 2 sen 1 ho2s. This would cause your runs rough and fuel mpg drop because the pcm keeps adding fuel to the left bank. Replacing the ho2s has been the fix for this and the plugs will most likely clear from the overfuel cond after a few min of run time. Your 06 has a 3/36 warr. so it shoul be covered anyway.

[Verdoro 68]

My mistake, Larry is right. It's not a knock sensor code, it's a lean code.