NC oxygen sensor after cat problem

[dannysunrise]

Done a ECU remap before changing the header, after installing the racing beat header, engine light is on due to O2 sensor bank 1 sensor 2 low response, is it the problem of changing the header or the sensor itself?

[Brian]

Not enough information, start with year of the Miata and tell us what else you have done, which midpipe, etc.

[dannysunrise]

2010 Miata , Racing beat Mid pipe and have done a ECU remap before installing the header!

[Brian]

So, no cat in the system now right? Racing Beat header has no cat, Racing Beat midpipe has no cat. That will make a code. You mentioned you did ECU reflash, go back to that tuner, they can turn off the code.

Normally we suggest using our 2.5 inch RoadsterSport midpipe with Cat, it has O2 sensor install positions before and after the cat to avoid the code, and outflows the smaller diameter no cat Racing Beat midpipe.

[dannysunrise]

I added a cat already! Before installing the header, I had done the remap and installed the mid pipe,no code error occurred!

[Brian]

Okay, so added the cat to the midpipe right? And you did O2 sensor install before and after that cat position? If so, and the sensors are in place before and after that cat then that should avoid code (assuming cat is healthy and extension of O2 wires is healthy too). Assuming all that, and assuming sensors in place before and after that cat, might be connection to sensor or might be issue with the sensor. Make sure wires to sensors are not pinch over at hard angles. Since it appears issue is sensor two, the tuner can turn that one off entirely, it is essentially just measuring function of that converter. You could even remove that second sensor entirely from the system and have the tuner just shut it off in the tune.

[dannysunrise]

Why o2 sensor after cat problem makes the rpm not stable when stopping at traffic light?

[Brian]

Sounds like a short in the wires used to extend the O2 sensors. Might be the wires are making contact somewhere with hot exhaust and protective coating has melted.

[ChristopherB668]

I too am having this issue.

I installed the max power header, so I purchased the 02 extension wires when I got the Helmholtz resonator, catted mid pipe. I checked both plug ends of the extension and both are in excellent shape. The front was heat taped for extra care and in perfect shape. The length of the wiring itself is routed under the exhaust tunnel heat shield against the body. That's also where the rear plug assembly was tucked and is also in excellent condition. The sensor itself shows no visible signs of damage and the wires coming off of it are straight and healthy. I disconnected the battery, disconnected the plugs, blew the connections out with compressed air, plugged everything back in...

Same code.
HELP??

[morrisg]

Is the code P0139? Slow response time? If so, my 2009 gets this code from time to time, maybe once a year. I just clear the code and everything runs fine. I have a PPE Long Tube Header, catted mid pipe and built my own wired extensions. I have the service manual and checking possible causes brings up nothing that is wrong on my car. I've checked the resistance of the wiring at the ECU connector and it's within specs. So I put it down to sloppy software matching between my tune and Mazda's code.