Whats the purpose of the O2 sensors on the Cataltic Converter.
01-17-2009, 08:13 PM
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Whats the purpose of the O2 sensors on the Cataltic Converter.
I am having a trouble code of PO174 on my 2002 f150 with the 4.2 engine. My truck is running nice and smooth. I replaced the 2 O2 sensors before the cats. It ran good for a few days and service engine soon light came back on. The trouble code was PO174 again. We hooked on a Snap-On scanner and it showed the MAF sensor working good and 2 upstream 02 sensors good.The scanner was showing no reading on the O2 sensors that are located on the Cats.Should they be showing some type of reading or what. Also is there a way to test the O2 sensors?The funny thing is that my truck is still running good even though it has a trouble code?For some reason it only does it when it is cold out side!
Last edited by Hobart63; 01-18-2009 at 12:03 AM. Reason: Left out information.
01-17-2009, 08:46 PM
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If you don't have a reading which would be them switching back and forth from high to low numbers [20%-90% range] then you might have a wiring problem.
I would also think your fuel mileage is getting worse.
As for the P0174 I would think that its a intake leak being you have a 4.2 but first I would get the cat problem fixed.
Just had a thought on what would tie the two problems together, have you checked for a exhaust leak? With a big enough leak you could peg a O2 out.
I would also think your fuel mileage is getting worse.
As for the P0174 I would think that its a intake leak being you have a 4.2 but first I would get the cat problem fixed.
Just had a thought on what would tie the two problems together, have you checked for a exhaust leak? With a big enough leak you could peg a O2 out.
01-18-2009, 09:14 AM
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Bill Wiltshire I have a quick question for you.The orings and the grommets that you said that you replaced on your 2002 F150, were they available at a auto parts store or did you have to get them at a Ford Dealer?Thanks for the information that you sent me in the PM . That sounds exactly like what my truck is doing.
01-20-2009, 09:14 PM
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Hobart63, Ijust went through the same bunch of crap, bro. I dont know how mechanicly inclined you are, but to me, It sounds like Its time for A new set of uppr and lower intake gaskets. I know it sucks man, but That cured my problem. And I'm telling you, you're discription sounded exactly like what was going on with mine. Kep on it, dont give up on it. Changing the gaskets looks scary, but they're not that bad. Its jst like workin on and old school motor except there is a fuel rail on the top.
01-20-2009, 11:13 PM
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Hobart63, Ijust went through the same bunch of crap, bro. I dont know how mechanicly inclined you are, but to me, It sounds like Its time for A new set of uppr and lower intake gaskets. I know it sucks man, but That cured my problem. And I'm telling you, you're discription sounded exactly like what was going on with mine. Kep on it, dont give up on it. Changing the gaskets looks scary, but they're not that bad. Its jst like workin on and old school motor except there is a fuel rail on the top.