What are the most likely causes of SPN 1569 FMI 31?

Active aftertreatment fault (DPF, DEF, SCR); Temperature or pressure out of range; Sensor fault triggering protection

How do you diagnose code SPN 1569 FMI 31?

1) List every active code and its order of occurrence — The root code preceding the derate is identified

SPN 1569 FMI 31

Q: What does truck fault code SPN 1569 FMI 31 mean?

The engine is deliberately limiting power. Engine protection torque derate is active. This code is never the cause: it is the consequence of another active fault, usually aftertreatment, temperature or pressure. Find the root code alongside it.

CAUTION

Torque derate

The engine is deliberately limiting power.

SPN 1569 FMI 31: The engine is deliberately limiting power. Caution: you can keep driving carefully, but the engine may derate; get it addressed soon.

Electrical · Engine

What it means

Engine protection torque derate is active. This code is never the cause: it is the consequence of another active fault, usually aftertreatment, temperature or pressure. Find the root code alongside it.

Most likely causes

Active aftertreatment fault (DPF, DEF, SCR)
Very likely
Temperature or pressure out of range
Likely
Sensor fault triggering protection
Likely

Tests, cheapest and most decisive first

1. List every active code and its order of occurrence
Expected result: The root code preceding the derate is identified
Tool: J1939 scanner

Read it off your own dash

Take one photo and DERATE tells you whether you can keep driving.

DERATE

DERATE assists. It does not replace inspection by a qualified technician.