Face Plugged DOC

[Nilao]

I found one of the the codes that will set it there is an issue with your DOC.

Fault Code: 2638

Aftertreatment Diesel Oxidation Catalyst Conversion Efficiency - Data Valid But Below Normal Operating Range - Least Severe Level. The temperature increase across the aftertreatment diesel oxidation catalyst (DOC) is lower than expected.
Active aftertreatment diesel particulate filter (DPF) regeneration will be disabled.
This fault code is logged when the conversion efficiency of the DOC is calculated to be less than that required to perform an effective regeneration.
Possible causes of this fault code include:
Soot plugging the front face of the aftertreatment DOC
Engine oil or fuel contamination of the aftertreatment DOC
A cracked or contaminated aftertreatment DOC
A damaged aftertreatment fuel injection system
A leaking exhaust system between the turbocharger and the DOC.