P0140 & P0171 Please help

[thaomyt]

can you someone please tell me how to fix this problems (p0140 & p0171). my car run a little rough.
thanks

[Nuswimr]

You are running lean, which means you have a fuel to air mixture problem with the p0171 code. I have a p0172 problem at the moment (running rich) and there are a few possible solutions. It could be a faulty oxygen sensor, or mass air flow sensor. It could also be a fuel regulator, or injector problem. I would say these are the most common things to have checked out. As you are not getting enough fuel into the mixture that's probably why your engine is running rough.

The p0140 warning is an oxygen sensor warning so definitely have that checked out first as it corresponds with both codes you are getting. Unfortunately I don't know of a way to check your oxygen sensor without replacing it, possibly a mechanic could test it with a meter to see if it's within parameters. Good luck sorry I can't be of more help.

[vannaksao]

You sure you're pulling a P0140?

[Nuswimr]

I just had my p0172 issue resolved, when running my car with a computer hooked up the oxygen sensor wasn't opening up. A new oxygen sensor solved my problem, and it sounds like it could be yours.

[thaomyt]

which o2 sensor are you talking about? I have 4 on my 01 Qx4.

[Chuck Tribolet]

P0140 says if you have P0171 fix that first.
P0171 is rear sensor, starboard (US passenger's) side.

Chuck