Hy...my car is a 2015 Mazda Carol hb36s same as (Suzuki alto ha36s).
I had modified the exhaust by removing the rear muffler a while ago.
Recently I have been getting a DTC code P0420
I have gone through cleaning the plugs, throttle, maf, etc...
What's left is to clean o2 sensor... what are methods and products you use for this task...
And also is it the exhaust modifications causing the DTC code to appear?
