P0137 code

2010 mazdaspeed3 after installing downpipe the PCM and p0137 code appeared. It is misfiring, getting bad gas mileage and running rich. Do you think getting a new downstream O2 sensor will fix this issue or do you think it’s the PCM?

 

What downpipe did you install? Catted or catless?

 

Catless

 

p0137 is your bank 1 sensor 2 o2 sensor. It monitors the state of the cat ( i think ). Since you got a catless downpipe, the ECU is reading abnormal values from the 2nd sensor. You can get an adapter that will help with the engine light by moving the 2nd o2 sensor further away from the exhaust stream (called an 02 sensor spacer i believe).

Did you get a tune for the new dowpipe? I think you will run into trouble if you don't tune the engine for the added exhaust flow. I would wait for someone to confirm with this but I am pretty sure its very very bad to run catless without a tune. I also heard the gen2 is super sensitive to small mods and a tune is highly recommended.

 

List your mods too

 

O2 standoff doesn't work so well on the gen2 speeds... As the others have said is it tuned? Are you running a Cobb map? Mod list?