SUBJECT: # 13073: question about o2 sensors in f-150

Submitted by spinrbait from SOUTH CAROLINA on 5/13/2008 8:44:00 AM

my check engine light came on my truck yesterday. i have heard the most common thing is an o2 sensor. what happens if you don't fix an o2 sensor and just keep driving it? i did a search on here, andeveryone i read had theirs fixed. does it harm your truck, or give you worse gas milage? i don't even know what an o2 sensor is. i assume it has something to do with oxygen. (truck has 114,000 miles.)
thanks for any help
spinrbait

1. 5/13/2008 1:42:00 PM Submitted by FreeOnBoard from TX says Mileage
   What year is your F150? Later models have 3 sensors, I think; one on each exhaust manifold and one after the catalytic converter. My '96 has just two, one on each exhaust manifold, which were replaced about 130k. If I understand correctly, the engine computer needs to know the remaining oxygen level in the exhaust so that it can adjust the fuel injection accordingly. Bad O2 sensors will therefore affect both power and mileage.

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2. 5/13/2008 2:02:00 PM Submitted by spinrbait from SC says ford
   it is a 98 4.6 v8. i thought this stuff had more to do with catalytic converters, and wouldn't really affect how the truck ran. heck a ford service tech even told me that years ago. but maybe he was wrong. i know i used to own a service company and had 10 or so rangers. the service guy told me not to waste my money because check engine light came on after certain milage. eventually everyone of those trucks had the check engine light come on. i never fixed a one, and they were ran like the energizer bunny. but they may have burned more fuel, i hadn't thought of that. spinrbait spinrbait

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3. 5/13/2008 2:03:00 PM Submitted by Greek #13637 from TX says O2 sensor
   Don't know the rules in your area but in the county I'm at in Texas a vehicle can not pass inspection if the check engine light is on.

   There are other very common causes for the light to come on. One of them is a lose gas cap. You can take the truck to a parts store and they'll hook it up to their computer and tell you what's acting up. Auto Zone and O'Reilly here do NOT charge you for the service. You could also disconnect the battery for about 15 minutes and let the computer reset. If the problem was intermitant you may get away with it. If not it will come back on.

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4. 5/13/2008 3:44:00 PM Submitted by Harumph #11038 from OH says Here is what will probably happen
   I have done your test.

   The truck will seem to run fine at times. You will notice it runs better in different temperature ranges and different humidity levels. From what I remember the worse range was 45-60 degrees with high humidity.

   Either way your engine will start to misfire most likely. Or least that will be the next set of diagnostic codes that are pulled from the computer.

   Then will come the inability to hold idle. The most annoying of the list. When you are stopped a light the RPMs will drop to a point of almost or complete stall.

   You can leviate this by throw the sucker in neutral while sitting at a light then dropping it into gear on green. This will last a bit longer until you are fanning the gas and popping it into gear.

   Then will come your best lesson. Or at least mine. It will decide to finally fail at the worst possible moment in the worst possible position. Stuck on a freeway in bumper to bumper traffic and dies.

   So I would say go with the flow and get it check/fixed. O2 sensor should run around 136.00 or least in that range.

   Good luck, and let us know which one it turns out to be. Dealerships and repair shops seem to have a real problem nailing down exactly which sensor is actually failing.

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5. 5/14/2008 11:08:00 AM Submitted by FreeOnBoard from TX says If you replace them yourself, Autozone has a special tool set you can borrow
   Other parts stores may also have it. I managed to get one side replaced with standard wrenches, but had to go back to the store and check out the tool set to get to the other one. Also, if you use anti-seize compound on the new ones, make sure none of it gets on the sensing element. As Greek recommends, read the trouble code(s) and make pretty sure thats what needs attention before you make the financial leap. Good luck.

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