PACCAR Fault Code P127A: EGR Pressure Difference – Data Valid But Too Low

Code details

Manufacturer

PACCAR (Kenworth & Peterbilt)

Applies to

PACCAR MX-13 (2017–2020)

Fault code

P127A

J1939 SPN

2659

FMI

1 — Data valid but below normal operating range (most 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 1 tells the shop the type of failure to test for: data valid but below normal operating range (most 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 P127B — EGR Pressure Difference – Data Valid But Too High
• PACCAR Fault Code P127C — EGR Pressure Difference – Data Erratic, Intermittent, or Incorrect
• PACCAR Fault Code P1400 — EGR Mass Flow – Estimated EGR Rate Too High
• International Fault Code SPN 2659 FMI 10 — EGR Slow Response Fault
• International Fault Code SPN 2659 FMI 14 — EGR System Flow Rate Error During Air Management Test
• International Fault Code SPN 2659 FMI 20 — EGR High Flow Rate Detected
• International Fault Code SPN 2659 FMI 21 — EGR Low Flow Rate Detected
• International Fault Code SPN 2659 FMI 10 — Engine Exhaust Gas Recirculation 1 Mass Flow Rate : Abnormal Rate Of Change