Contour Enthusiasts Group Archives Forums General Troubleshooting CEL p0171

hello iam new member any help with my problem would be great. 98 mystique 2.0 zetec. check engine light came on about two weeks ago. went to autozone to have the code read p0171 and they told me bad o2 sensor. Replaced both and light came back on the next day.Replaced plugs,wires,fuel filter,air filter,pcv. cleaned TB. checked out MAF but not to sure on how to test it. car seems to run fine but the light keeps coming back on after i clear the code.

Welcome to CEG!

P0171 System Too Lean - Bank No. 1.

With the work already done, I suggest that you clean the MAF sensing element and check for vacuum/intake leaks.

Several techniques for MAF cleaning to be found with a search.

Air leaks can be caused by a loose or missing dipstick or oil cap. Leaks at the PCV valve or fresh air tube are fairly common. The PCV valve has a short rubber hose under the exhaust manifold that becomes affected by the heat.

If it is not affecting driveability yet just start ruling these out.

thnaks for the info. i will give it a try and let you kowm if it works. usally takes a day or so for the light to come back on

thnaks for the help. cleand MAF and cel light has been out for two days.

Do you need to disconnect the battery for 30 minutes after cleaning the MAF? Or will the light go off if cleaning it is the problem.
I have a code P0171 as well.

disconnect the battery before you clean it and wait about 10 min. Start with this before you spend money on other things. carb cleaner and electro wash will only run you less then 10 bucks.