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i just got my codes read at auto zone, and the code came out as p0139, says its the bank 1 sensor 2. it also says under gen. description that its before the cat.

when i looked at my sensors, i can only see two O2 sensors one before and the second one after the CAT. is there a third sensor, if so is it on the exhaust pipes somewhere? or is it on the intake pipe before it goes in the engine?

i have read a lot about this damn sensor and read a lot about the codes, but i cant see how it would be sensor 2 if the 2nd sensor is located after the CAT, when it deliberately said it was before the CAT......

any info guys i need to get this thing done, cause if its before the CAT, im probably running a rich or lean engine..... bad mileage....

Thanks Oz

 
Rep Power: 280

I'm pretty sure you have a problem with the primary 02 sensor (pre cat). Remember those auto zone scanners are universal and may not be the exact same description as a honda specific scanner. We have 2 02 sensors. One pre cat and the secondary is on the cat converter. That is for the EX. The LX and DX may be different since your cat is on the header.

 
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yea i believe there are only two cause i could not find another one. the first one is on the manifold the second one is after the cat or on the cat, cant get a good look at it.

is it safe to switch them and see if it tells me a different code? that is if the wiring can reach, OZ

 
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sensor is like $150. can i just put a bolt on header in there and call it a day?

 
Rep Power: 280

What model do you have? If you have a DX or LX if you put an aftermarket header you will lose your catalytic converter and throw a code. (There are ways to get around the code.) I would solve the CEL problem you are having before you buy a new header. There is a problem with your car so take it to a mechanic.

 
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two.

 
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so the code says BANK 1 SENSOR 2. The second sensor is obviously after the cat. and it cost $336 to replace by myself. damn this sucks!!!!

what to do....

1. Does this code mean that the sensor is bad or does it mean that the exhaust emission is bad? or both.....

2. if its just bad exhaust is there a way i can overide this?

 
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its probably the sensor, and u can get one for cheaper from a parts store, since its not the heated sensor it shouldnt be that expensive

 
Rep Power: 387

browse through the exhaust link in my sig...

 
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what is a heated sensor?

 
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a just as it sounds, its heated, i believe to match engine temp, but its that simple, its just more when its heated, and only the primary is heated

 
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ok i cant find any damn place that has them for cheap not even ebay. anyone tell me where i can get one?

 
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spend the money and just get it, dont be cheap

 
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hey dude,.. i dont know where your getting 330 bucks to change an 02 sensor, i bought mine for like 50 bucks at autozone and i bought the sucket and took it off myself, it is easy to do so, the one in front is super easy and the one on the bottom is also easy, just have to jack up the car for the bottom one,.. again i spend less then 125 fo the 02 sensor and for the sucket and thats that,.. enjoy do it yourself...

 
Rep Power: 221

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