i have a buck skaylark 1997 the check engine light is on anmd the ets light i had the code read and it was 420 catalys systems efficiency below threshold (bank 1) how do i fix it
Year : 1996Make : BuickMake (other): Model: skylarkEngine: 4cly
DTC P0420 - catalyst efficiency below threshold is caused by only three things:
check for exhaust leak between exhaust manifold and convertor and repair as necessary. If ok, check wiring harness on O2 sensor for damage- melted from touching exhaust, cut or chaffed wiring. Repair as necessary.
If the above are ok, replace catalytic convertor.
over 20 years experience as a Automotive shop manager and tech/JA Mentor