03 December, 2025PACCAR MX (2004 Emissions) Fault Code: P151C Aftertreatment System – DEF Level Too Low PACCAR MX (2004 Emissions) Fault Code: P151C Aftertreatment System – DEF Level Too Low SET CONDITIONS:The DEF level is less than 20% of the DEF tank volume. DIAGNOSTIC CONDITION:This diagnostic runs continuously when the ignition is on. RESET CONDITION:This DTC becomes inactive after the ignition is keyed on and the volume in the DEF tank is above the set condition value. POSSIBLE CAUSES:Empty DEF tank ADDITIONAL INFORMATION:The driver has been informed by a flashing warning. Compartir en Facebook Se abre en una nueva ventana. Compartir en Twitter Se abre en una nueva ventana. Guardar en Pinterest Se abre en una nueva ventana. Regresar al blog