SPN 3363 — Aftertreatment 1 DEF Tank Heater
System: Aftertreatment / DEF
The coolant valve or electric element that thaws and warms DEF in the tank so it can be pumped in cold weather.
Can I keep running it?
MEDIUM — fix soon
In warm weather you can usually keep running; in freezing weather DEF may not thaw and derates can follow.
Likely causes
- Stuck or failed coolant heater valve
- Open electric heater element in the tank header
- Wiring or connector fault at the tank header
- Header replaced without reseating seals and connectors
Checks & fixes (easiest first)
- Command the heater with a scan tool and feel/measure the coolant line warming
- Measure heater element resistance against spec
- Inspect header connectors and O-rings, especially after recent tank work
- Check DEF tank temperature reading for plausibility
Common FMIs with SPN 3363
- SPN 3363 FMI 3Voltage above normal or shorted high
- SPN 3363 FMI 4Voltage below normal or shorted low
- SPN 3363 FMI 5Current below normal or open circuit
- SPN 3363 FMI 7Mechanical system not responding or out of adjustment
- SPN 3363 FMI 16Value too high (moderately severe)
- SPN 3363 FMI 18Value too low (moderately severe)
Related codes
- SPN 1761Aftertreatment 1 DEF Tank Volume
- SPN 4334Aftertreatment 1 DEF Doser Absolute Pressure
- SPN 5246Aftertreatment SCR Operator Inducement Severity
Troubleshooting guides
FAQ
What does SPN 3363 mean?
SPN 3363 is Aftertreatment 1 DEF Tank Heater. The coolant valve or electric element that thaws and warms DEF in the tank so it can be pumped in cold weather.
Can I keep running with SPN 3363?
In warm weather you can usually keep running; in freezing weather DEF may not thaw and derates can follow.
What causes SPN 3363?
Stuck or failed coolant heater valve; Open electric heater element in the tank header; Wiring or connector fault at the tank header; Header replaced without reseating seals and connectors.