Detailed guide for SPN 3703 FMI 31
Back to top ↑This one is painfully common: regen inhibit gets turned on for a site and forgotten. Fix it now or you’ll meet SPN 3719 soon.
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Share ↓SPN 3703 FMI 31Severity: Warning
SPN 3703 FMI 31: Active regeneration inhibited – inhibit switch/circuit active
Quick Answer
Active regeneration inhibited – inhibit switch/circuit active
Code
SPN 3703 FMI 31
Severity
Warning
Applies to
Check OEM application
Can I drive?
Driving suitability is not established by this code alone.
Common Symptoms
- Regen requested but won’t start
- Soot climbs over time
- Eventually derate risk
Likely Causes
- Regen inhibit left ON
- Switch circuit fault
- Operator habit
Common Fixes
- Confirm inhibit is OFF
- Test switch circuit and wiring
- Run regen once conditions are correct
Full technical sections↓
What does SPN 3703 FMI 31 mean?
Back to top ↑Active regeneration inhibited – inhibit switch/circuit active
Images for SPN 3703 FMI 31 (location, common failures)
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Aftertreatment exhaust line schematic. Regen inhibit prevents the DPF from cleaning itself.
Credit: Wikimedia Commons • License: License on file page
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