Hello my friend
Ive watched countless hours of your videos and I've been a fan for a long time!
I recently bought a 2016 cx5 touring and there's a p0421 code that pops up intermittently
Ive tried:
- cleaning the fuel rail
- cleaning the intake manifold
- changing the catalytic converter from underneath the car
- changing the o2 sensors
- putting cataclean
- 93 gas
- changing the fuel pump ( to change the fuel filter)
- had the pcm flashed to the latest update
Nothing has worked do you have any expert recommendations for me?
Thank you my friend,
-Sid
try the troubleshooting steps here
Did any of those parts test as being bad or were you just loading up the parts cannon? Did you install OEM parts? You can find diagnostic information for P0421 in the link below.
https://www.carparts.com/blog/p0421-code-warm-up-catalyst-efficiency-below-threshold-bank-1/
That code is similar to P0420:
https://www.walkerexhaust.com/support/tech-tips/diagnosing-catalytic-converter-p0420-code.html
https://www.carparts.com/blog/p0420-code-catalyst-system-efficiency-below-threshold-bank-1-2-2/
Also see this TSB for 2014-2016 Mazdas and P0421, check your VIN to see if your vehicle is listed as affected:
https://mazda.oemdtc.com/376/check-engine-light-on-with-dtc-p0421-2014-2016-mazda
