What causes a SPN 3131 code?

SPN 3131 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a SPN 3131 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3131 active.

How do I fix SPN 3131?

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

J1939 SPN

SPN 3131

J1939 SPN 3131 — Body/Chassis parameter

What it means

Aftertreatment 1 SCR AdBlue/DEF Tank Heater Control Valve - Voltage Below Normal, or Rate of Change Abnormal. This relates to the valve that controls engine coolant flow to the DEF tank to thaw it in cold weather.