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Hello everyone, I’ve got a 2005 civic LX with the 1.7 SOHC non vetc (D17A2) (268,000 miles) and I’m having problems with my downstream oxygen sensor. Cleared the code and it came back within the day. Haven’t replaced it yet and wondering why it would’ve went bad. Thanks!

 
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Old age

 
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So I should just replace it and it should fix the problem?

 
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What fault code are you seeing?

 
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I don’t remember. I’ll look tonight when I get home. P0 something I believe. I just ordered a stainless steel header for it so I’m getting rid of the cat completely. If it’s clogged up that’ll fix it lol

 
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Without a cat you will have a fault for sure, P0420: Catalyst System Efficiency Below Threshold. If that is your current fault it's not due to a bad sensor but a bad cat.

 
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you should replace it.
as for if it will solve the problem, you tell us after you replace.

 
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Ok, I’ll let you know when I put my header on. If I throw a catalytic converter code after I take it out completely would it hurt the car? Should I adjust my valves as well when I put it on and does anyone know the resistance on the O2 sensor to trick the computer to think everything’s normal? I don’t really want any dash lights on. I appreciate you guys!

 
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No it will not hurt anything without a cat. It will run as normal you would just have a fault code and engine light on. You also won't pass emission testing if you have that in your state.

I don't see what that has to do with installing a header. The valve lash can be adjusted at any time. Recommended every 110,000 miles or whenever they become noisy.

It's not that simple. There is a method to trick the sensor that I was going to try but never got around to doing. Basically you remove the sensor and install a couple spark plug non foulers. Essentially a spacer that moves the sensor further from the cat. Here's a link explaining this process. Quick note, this is not a legal fix.
https://www.civicforums.com/forums/2...on-w-pics.html

 
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Ok! I’ll be doing all that here before long. Thank you guys for all the help!

 
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O2 sensor spacer does work on a 6th gen for sure, not sure about 7th Gen but it probably will

 
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Should I put the moded spark plug non-foulers on the top and bottom o2 sensors or just the downstream?

 
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Downstream, that's the one that deals with the cat

 
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Alrighty sweet, thank you. Bought 2 sets just in case.

 
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Check what fault you have first. If it isn't P0420 it could just be a bad sensor.

 
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So the o2 code is a P0139. Turns out it’s a D17A1 and not the A2, would that make a difference in the sensor? I work at Napa and it got one for a A1 and a different one for the A2

 
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Probably the wire length, however you only want to use a Denso or ntk sensor, check which is on your car, use nothing else

 
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Ok thank you.

 
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Got the DNA exhaust installed. No more cat, no more problems! 02 sensor problems fixed and no more light. Also for everyone with an 05 civic, there’s not enough space for the 2 spark plug non foulres so I’m just running one and it seems to be working fine.