Question about Ford Explorer
The check engine codes reproted are telling you that the mixture has too much air (lean mixture). Test and eventually repair or replace parts that may be contributing to the problem.
Test fuel pump and fuel pressure. If fuel delivery is not regular or if pump is broken you may get a lean code from the O2 sensors. Fuel pressure is tested placing an hand pressure gauge within fuel lines.
Ensure that distribution is OK and that there is no misfire. In that case you should get a msfire code along with the lean code, but you never know the misfire does not get detected by PCM (main computer).
Check air intake and sensors, if the MAF or AIT sensors are not connected or malfunctioning you can get a lean mixture.
Check the vacuum system. If there is a leak, then the vacuum will be sucking air from the leak and this may return a lean code.
Check IAC and EGR valves.
I think I listed all most common factors that can return a lean code from both O2 sensors ( that tells you that the sensors are OK).
Posted on Sep 08, 2010
Thanks for using FixYa. Codes PO171 and PO174in your Ford means a bad Mass Air Flow (MAF) sensor as a bad sensor will cause the vehicle not to start. Also these codes indicate a lean fuel mixture. Check for vacuum leaks by spraying carb cleaner around the intake manifold and any vacuum lines. If you do not find any intake leaks, replace the mass air flow sensor. Please do accept the solution if the issue is resolved or post a comment for further assistance.
Posted on Aug 31, 2010
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Posted on Jan 02, 2017
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