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Old 07-23-2013, 11:25 AM   #1
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02 sensor problem??

I have a question my car is running like it only has 30hp it has a check engine light so I had them read it came back for both 02 sensors.heres my question would the 02 sensors really rob me for that much power or should I be looking at the cat also?? anyone else ever have this problem?


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Old 07-23-2013, 01:07 PM   #2
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02 sensors are read by the computer and the car then adjusts the fuel mixture based on the data, so if you are getting bad data, then that will mess up your air/fuel mixture, which will probably rob you of power.

If both 02 sensors are bad, then it is probably not your cat, as one sensor is pre-cat, and one is post cat, IIRC.

If both sensors are bad, it might be an indication of a problem that is damaging the sensors, such as an internal antifreeze leak, oil consumption, or a rich fuel mixture, so if both sensors are bad, you might want to check for a root cause. but they might just both be bad....

Double check your code and description in this thread:

http://www.focusfanatics.com/forum/s...ad.php?t=59286
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Old 07-23-2013, 01:20 PM   #3
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yea well that makes sense. it recently had a head gasket failure that I fixed, but at the time it didn't have this problem. I mean I put on a least a few hundred miles on it since the repair
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Old 07-23-2013, 02:11 PM   #4
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that could have caused coolant or oil or both into the cylinders, which could damage both o2 sensors. makes sense, even though it has been a while.

you should be able to replace both sensors for about $100, or so. Swaping them out sounds like a very easy job.

But before you spend the money, I would make 100% sure that the new head gasket is not leaking. IIRC people have had problems with new head gaskets leaking if they did not remove every little bit of the old gasket, or torqued the bolts incorrectly....

Hope that helps
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Old 07-23-2013, 02:35 PM   #5
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yea I was thinking a compression test it hasn't over heated or anything since the head gasket was done. and the check engine light shot just the code for both o2 sensers, I just don't wanna replace them just to find out the cat was the problem u know? because I hear the cat causes similar problems with the lost of power and all.
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Old 07-23-2013, 02:51 PM   #6
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If it was just the downstream sensor, a bad cat is a great explanation, but I cannot see how a cat would damage the upstream sensor. Not saying it's not possible, just saying it does not make sense to me.

try pulling the sensors and visually inspecting them, that might tell you something.

also, post your actual CEL code, that would help to know.
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