how do I clear trouble code p0420 on a 2013 chevy durmax

Question

my truck has 287,000 miles and I do most of the work on my truck and just need to know how to clear this code.

Answer 1

P0420 Catalyst system below efficiency

For a Diesel engine this a diesel oxidation catalyst , the way to clear this code is with scan tool, as long as this code is present the ECM will not allow a regeneration. If you have a scan tool that can read EGT sensor you can easily diagnosis whether you would need a catalyst by comparing EGT sensor readings.

With EGT sensor 4 compare it to EGT sensor 2 if it is within 100 degrees C and is within 100 degree C of EGT 1 you replace the catlytic convertor.