03 December, 2025PACCAR MX (2004 Emissions) Fault Code: P1514 Aftertreatment System – DEF Dosing Malfunction Detected PACCAR MX (2004 Emissions) Fault Code: P1514 Aftertreatment System – DEF Dosing Malfunction Detected SET CONDITIONS:This DTC becomes active if the DTC from which it originates has been active for a certain time. RESET CONDITION:This DTC becomes inactive as soon as the DTC from which it originates has become inactive. ADDITIONAL INFORMATION:IMPORTANT: Do not troubleshoot this DTC since it originates from another active DTC. 1. This DTC only activates a warning for the driver.2. This DTC becomes active simultaneously with an active DEF dosing system related DTC. Share on Facebook Opens in a new window. Tweet on Twitter Opens in a new window. Pin on Pinterest Opens in a new window. Back to blog