Detailed guide for SPN 3363 FMI 4
Back to top ↑Voltage low is usually wiring. Salt and moisture destroy DEF heater connectors.\n\nRepair the electrical issue first. A new heater will not fix a rotten connector.
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Share ↓SPN 3363 FMI 4Severity: Warning
SPN 3363 FMI 4: DEF tank heater voltage low / short to ground
Quick Answer
DEF tank heater voltage low / short to ground
Code
SPN 3363 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 on cold days
- Possible inducement if it persists
- Heater may not operate
Likely Causes
- Short to ground in harness
- Open circuit or poor connection
- Water intrusion in connector
Common Fixes
- Inspect harness routing and rub points
- Dry/clean connector and repair pins
- Load-test power and ground
Full technical sections↓
What does SPN 3363 FMI 4 mean?
Back to top ↑DEF tank heater voltage low / short to ground
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