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2000 Grand Prix GT 3.8L PO174

07-14-2012, 08:01 PM

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7:47 PMthis is

Hello all... Have a 2000 Grand Prix 3.8L. Terrible gas mileage, shifting issues (under load ex. going uphill - wont downshift). Code PO174 came up. Any thoughts?

Tech II
07-15-2012, 07:28 AM
Only P0174? P0171 is not set, too? No P0300?

This means you are seeing a lean condition on the even numbered banks....could be a bad injector, vac leak on that side of the engine, could even be a bad O2 sensor on that side....

Since P0171 is not set, it is not a situation that would be common to both banks, like fuel pressure, MAF, etc.

07-15-2012, 07:29 AM
Welcome to AF!!

There is a good possibility that your Mass Air Flow (MAF) sensor is bad and needs to be replaced. The computer is detecting a lean condition causing the engine to run too lean and therefore you have a lack of power. As for the shifting issues check and make sure that the trans fluid level is correct. If you have not changed the filter and fluid in the car it may be a good time to do so. A can of Sea foam transmission additive may also help clean thing us a bit before changing the filter and fluid. Just don't let anyone talk you into a transmission flush especially if the car has high miles.

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