Codes 0171 and 0174 | Ford Explorer Forums - Serious Explorations

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Codes 0171 and 0174


September 29, 2012
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City, State
Fort Smith, Arkansas
Year, Model & Trim Level
1999 Explorer 4.0 V6 OHV
Getting codes 0171 and 0174 on my 1999 Ford Explorer with 4.0 V6 OHV with 136k miles. I cannot detect that the engine is running bad or any different than it has been.

This appears to be a cold weather related issue as this same thing happened last fall and intermittently throughout the winter. I would check something and reset the code but it would eventually come back on. When the weather warmed up the codes did not come back. I figured that maybe cleaning and checking the hoses had fixed it. codes over the summer at all. Now with the weather turning cold again i start getting the codes again.

Wondering if anyone else has experienced this or has any ideas?

You need to replace your intake manifold gaskets. They leak when it gets colder out and stop/don't leak as much when it's warmer out.