Code 171...Please help!!

I got the code 171 from Autozone and I know it means that the 1st bank is too lean. What should I replace? The sparkplugs? Anything else? And about 2 months ago another code came up and I had to replace my mass airflow sensor. Does it have anything to do with that?

Need some more info. Is the CEL on all the time? How does it drive? Does it hesitate when you hit the gas? Does it seem to starve for fuel? The MAF sensor at the intake measures (like it says) the amount of air going into your engine. I think it might have something to do with the CEL light on. Disconnect the negative side of the battery for 5 minutes. This will reset the computer. If the CEL was a one time thing and not ongoing, it will go out and not come back on. I don't think replacing the plugs will help. IF the plugs were a fault the motor would run too rich, not lean.

Yes, the CEL light has been on for a week or so. The car shakes a lot and it does hesitate when I hit the gas. I do believe that the car is starving for fuel. I tried a fuel injector but it didn't help. Thank you for your help.

Often this code is associated with the EGR system being messed up. (BTW, you only have "bank 1". V-6, and V-8 engines would also have a "bank 2" ... and could have both associated codes: P0171 & P0174.)

Just as a test to see if the engine runs better (the code won't go away, in fact, the test will give you more temporary codes) ... pull and plug the vacuum hose that operates the EGR valve. If the car runs better, then the EGR system is VERY suspect. After the test, reconnect the vacuum hose.

The intake manifold can also have a plugged EGR path inside ... depends on the year model. Guess you didn't want to share the year and engine info???

Well the car is a 2001. I'm not sure what engine is has off the top of my head. The man at autozone told me that with me only getting the code 171, that later on I would probably get the code 174. I haven't checked the codes since then though.

I believe (for the USA) in 2001 there were only 4 cyl gasoline 2.0 liter engines. No "Vee's". Therefore, you will never get a "P0174" ... except by total error ... which occassionaly happens but not often.