What causes a SPN 3426 code?

SPN 3426 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 3426 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3426 active.

How do I fix SPN 3426?

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.

J1939 SPN

SPN 3426

J1939 SPN 3426 — Body/Chassis parameter

What it means

Aftertreatment 1 Diesel Exhaust Fluid Tank Heater Relay Control Circuit. Note: While the J1939 standard lists 3426 as Aftertreatment Heater Relay, many manufacturer-specific implementations (like Paccar or Cummins) treat 3426 as an Electrical System/Battery Potential issue related to the body/chassis power supply.