PACCAR (Kenworth & Peterbilt)
PACCAR fault code
SPN 1072 / FMI 4
PACCAR Fault Code P3439: MX Engine Brake Solenoid Valve Cylinder 5 – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A13)
P3439 on PACCAR (Kenworth & Peterbilt) engines means: MX Engine Brake Solenoid Valve Cylinder 5 – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A13). The failure mode (FMI 4) is “voltage below normal, or shorted to low source”.
Code details
- Manufacturer
- PACCAR (Kenworth & Peterbilt)
- Applies to
- PACCAR MX-13 (2013–2016)
- Fault code
- P3439
- J1939 SPN
- 1072
- FMI
- 4 — Voltage below normal, or shorted to low source
- Truck models in source
- Kenworth T680, T880, W900, T800; Peterbilt 579, 389, 567, 367
What to do next
- Read active and inactive codes with the OEM service tool and note the occurrence count.
- FMI 4 tells the shop the type of failure to test for: voltage below normal, or shorted to low source.
- Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.
Get this code diagnosed
Send one request and nearby diesel shops and mobile mechanics can quote the repair.
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Related fault codes
- PACCAR Fault Code P3405 — MX Engine Brake Solenoid Valve Cylinder 1-3 – Current Too Low or Open Circuit on ECU (D420) Pin (A17)
- PACCAR Fault Code P3407 — MX Engine Brake Solenoid Valve Cylinder 1-3 – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A17)
- PACCAR Fault Code P3408 — MX Engine Brake Solenoid Valve Cylinder 1-3 – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (A17)
- PACCAR Fault Code P3445 — MX Engine Brake Solenoid Valve Cylinder 4-6 – Current Too Low or Open Circuit on ECU (D420) Pin (A20)
- PACCAR Fault Code P3447 — MX Engine Brake Solenoid Valve Cylinder 4-6 – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A20)
- PACCAR Fault Code P3448 — MX Engine Brake Solenoid Valve Cylinder 4-6 – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (A20)
- PACCAR Fault Code P3405 — MX Engine Brake Solenoid Valve Cylinder 1 – 3 Current Too Low or Open Circuit on ECU (D420) Pin (A17)
- PACCAR Fault Code P3407 — MX Engine Brake Solenoid Valve Cylinder 1 Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A17)
Source: PACCAR MX-13 2013–2016 fault code list (Diesel Laptops). See also OBD-II codes.