PACCAR Fault Code P3783: Diesel Oxidation Catalyst (DOC) – Data Valid But Too High, Moderately Severe

Code details

Manufacturer

PACCAR (Kenworth & Peterbilt)

Applies to

PACCAR MX-13 (2017–2020)

Fault code

P3783

J1939 SPN

4766

FMI

16 — Data valid but above normal range (moderately severe)

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 16 tells the shop the type of failure to test for: data valid but above normal range (moderately severe).
• Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.

Related fault codes

• PACCAR Fault Code P3753 — Exhaust Gas Temperature Before DPF – Voltage Too High or Short Circuit to Supply
• PACCAR Fault Code P3754 — Exhaust Gas Temperature Before DPF – Voltage Too Low or Short Circuit to Ground
• PACCAR Fault Code P3755 — Exhaust Gas Temperature Before DPF – Data Erratic, Intermittent, or Incorrect, Not Changing During Operation
• PACCAR Fault Code P3779 — Exhaust Gas Temperature Before DPF – Data Valid But Too High, Least Severe
• PACCAR Fault Code P3780 — Exhaust Gas Temperature Before DPF – Data Valid But Too High, Most Severe
• PACCAR Fault Code P3782 — Exhaust Gas Temperature Before DPF – Data Valid But Too High, Moderately Severe
• International Fault Code SPN 4766 FMI 10 — Catalyst System Efficiency Below Threshold