CODE P0420

1999 Honda CRV

Engine Performance problem
1999 Honda CRV 4 cyl All Wheel Drive Automatic 150000 miles

i have a code p0420 that says catalyst efficiency below threshold(bank 1). What is this?
Joey little
February 15, 2009.

Usually a faulty O2 sensor will throw this code. Need to check your oxygen sensors. Follow the link below to learn how to test an oxygen sensor.

If sensors are OK, need to flow test the catalytic converter..

Thanks for using!

Feb 15, 2009.