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PACCAR MX-13 Fault Codes — Top 30 SPN/FMI Codes

The PACCAR MX-13 powers Kenworth T680/T880 and Peterbilt 579/389 trucks. This reference covers the 30 most frequent SPN/FMI fault codes with symptoms, causes, and step-by-step diagnostic procedures.

PACCAR MX-13Kenworth / Peterbilt30 Fault Codes

Fault Codes Covered

System Categories

Critical Faults

Aftertreatment Codes

PACCAR MX-13 Engine Overview

Engine Specifications

Displacement12.9L (787 cu in)
ConfigurationInline 6-cylinder
Power Range405–510 HP
Torque Range1,450–1,850 lb-ft
Emission StandardEPA 2010+ / GHG17
AftertreatmentDPF + SCR + DEF

Common Applications

Kenworth T680, T880, W900
Peterbilt 579, 389, 567
Long-haul and regional trucking
Vocational and specialty applications

Top 30 PACCAR MX-13 Fault Codes

Click any fault code for full diagnostic procedures, wiring tests, and repair steps.

SPN	FMI	Description	System	Severity
157	18	Fuel Rail Pressure — Low (Moderate)	Fuel	High
157	1	Fuel Rail Pressure — Low	Fuel	High
3031	0	DPF Soot Load — High	Aftertreatment	High
4364	18	SCR Efficiency — Below Threshold	Aftertreatment	High
5246	31	DEF Dosing Agent Concentration — Low	Aftertreatment	High
3216	2	SCR Inlet NOx — Erratic	Aftertreatment	High
3226	2	SCR Outlet NOx — Erratic	Aftertreatment	High
110	0	Engine Coolant Temperature — High	Cooling	Critical
100	1	Engine Oil Pressure — Low	Lubrication	Critical
102	1	Intake Manifold Pressure — Low	Turbo/Air	High
1189	7	VGT Actuator — Mechanical Not Responding	Turbo/Air	High
3480	5	HC Doser — Current Below Normal	Aftertreatment	High
3484	31	Aftertreatment Regeneration Inhibited	Aftertreatment	Medium
3232	18	SCR Efficiency — Below Threshold (Severe)	Aftertreatment	Critical
3230	0	SCR Operator Inducement — Severity 2	Aftertreatment	Critical
636	2	Camshaft Speed/Position — Erratic	Engine	High
637	2	Crankshaft Speed/Position — Erratic	Engine	High
105	0	Intake Manifold Temperature — High	Turbo/Air	High
101	0	Crankcase Pressure — High	Engine	High
175	0	Engine Oil Temperature — High	Lubrication	High
94	1	Fuel Delivery Pressure — Low	Fuel	High
97	0	Water in Fuel — High	Fuel	High
1079	3	Sensor Supply Voltage 1 — High	Electrical	High
639	9	J1939 Network — Abnormal Update Rate	Electrical	High
1109	31	Engine Protection System — Shutdown	Engine	Critical
1111	31	Engine Protection System — Derate	Engine	High
3360	4	DEF Tank Level — Voltage Below Normal	Aftertreatment	High
3490	4	DEF Heater — Voltage Below Normal	Aftertreatment	High
167	1	Battery Voltage — Low	Electrical	High
1640	7	Fan Clutch — Mechanical Not Responding	Cooling	High

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