Detailed guide for SPN 4344 FMI 4
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Share ↓SPN 4344 FMI 4Severity: Warning
SPN 4344 FMI 4: DEF line heater 3 voltage low / short to ground
Quick Answer
DEF line heater 3 voltage low / short to ground
Code
SPN 4344 FMI 4
Severity
Warning
Applies to
Check OEM application
Can I drive?
Driving suitability is not established by this code alone.
Common Symptoms
- DEF heater fault
- Heater circuit reports low voltage
- SCR warnings during freezes
Likely Causes
- Short to ground
- Connector contamination
- Harness damage
Common Fixes
- Inspect harness near mounts/heat shields
- Repair insulation damage
- Replace heater only after circuit checks
Full technical sections↓
What does SPN 4344 FMI 4 mean?
Back to top ↑DEF line heater 3 voltage low / short to ground
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