1999 exped check engine lgiht

[lifewitlooie]

looking for help.. my friends expedition is having problems.. check engine light came on. pulled codes. forgot number code . said engine is running lean. changed 02 sensor. engline light went away. came back on 2 days later. mass air flow sensor maybe?? need help thanks or a link to better info i could search through... maybe a flow chart or something for a lean running engine thanks

[RickMN]

Here's how to clean a MAF sensor:Free-Auto-Repair-Advice: How to clean your MAF sensor

However, a lean code is usually caused by a vacuum leak. You've made the common mistake of thinking that the O2 sensor was the cause of the problem rather than the result. But at least they're not that expensive.

Now it's time for your friend to invest a few bucks in an online manual and do the diagnostics for the code he got. That will cost far less than throwing unneeded parts at it.

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