'99 4.0l Explore Eng Code 171 & 174
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'99 4.0l Explore Eng Code 171 & 174
The Check Engine lite came on. ~ 74,000 miles on my '99 Explorer. AutoZone checked out codes as PO171 & 174 (system adaptive fuel too lean on bank 1 & 2).
Recently had problems with motor revving up way too high during cold starts. Mechanic replaced EGR valve and cleaned intake and problem went away. About one month later (now)...the check engine lite has come on as mentioned above.
Probable causes according to AutoZone is MAF sensor or O2 Sensors before (& after?) catalytic converter.
Any suggestions before I buy two upstream sensors??
Cabbie 2169
Recently had problems with motor revving up way too high during cold starts. Mechanic replaced EGR valve and cleaned intake and problem went away. About one month later (now)...the check engine lite has come on as mentioned above.
Probable causes according to AutoZone is MAF sensor or O2 Sensors before (& after?) catalytic converter.
Any suggestions before I buy two upstream sensors??
Cabbie 2169
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Joined: Dec 2002
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From: fairbanks usa
clean the maf sensor before you spend any money it's the thing by the air filter with 2 wires. try spraying an electrical contact cleaner on the wires and alowing to dry. i don't think o2 sensors are the problem ford has had a ton of problems with these things getting contaminated. hope this saves you some time and money
Senior User
Joined: Dec 2002
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From: fairbanks usa
you'll need a scan tool if you want to turn it off right away. the light will eventually go off on it's own if you hit the problem but it takes something like 40 trips. it's best to use the scan tool(auto zone) to kill the light because then you'll know after a few trips if you fixed the problem.
Fleet Mechanic
Joined: Oct 2003
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From: CentralEastern Utah
You can clear your codes by unhooking your battery for a few minutes and then rehooking it back up. Works on my 2000 Exp. As far as your trouble, sounds like you ought to check out your IAC. Their is some good info on it on the main forum page in a "sticky". The MAF is located on your intake right after your filter. When you clean it you must make sure its dry before replacing it. A new one is pricey. My bet is on the IAC though.
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From: fairbanks usa
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You need to get to Ford dealer FAST
Your codes po171/174 are falling under a less known campaign #00m12, covered under a Ford self-imposed warranty[ 5yrs and I believe 75000 miles.] ( lower intake gaskets) Also ask about campaign #00m12c2.1, for the timing chain tensioner replacement.
Your codes po171/174 are falling under a less known campaign #00m12, covered under a Ford self-imposed warranty[ 5yrs and I believe 75000 miles.] ( lower intake gaskets) Also ask about campaign #00m12c2.1, for the timing chain tensioner replacement.
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