Code p0420 2021 2500 6.7

[Liston]

Dealer can’t keep my check light from coming on. Always code p0420
They claim to have replace many parts but lamp come back the next day. Has anyone had this issue.Thanks for any advice.

 

[06 Dodge]

Dealer can’t keep my check light from coming on. Always code p0420
They claim to have replace many parts but lamp come back the next day. Has anyone had this issue.Thanks for any advice.

Having a list of what parts have they changed would help

 

[Dennis Shellito]

I agree with 06 Dodge that a list of parts that the stealership has replaced would be a start. Having repeated this, the fault that is kicking the CEL is caused by an higher than acceptable (per system parameters) level of carbon and other harmful elements in the exhaust flow. The cause could be anything from a faulty O2 sensor, or a damaged catalytic converter or an exhaust leak. Though less likely, it could also be a glitch in the system.