Detailed guide for SPN 4334 FMI 2
Back to top ↑If DEF pressure is unstable, dosing becomes inconsistent.\n\nStart with wiring and connector checks, then verify the pump can build and hold steady pressure.
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Share ↓SPN 4334 FMI 2Severity: Warning
SPN 4334 FMI 2: DEF dosing pressure data erratic (unstable signal)
Quick Answer
DEF dosing pressure data erratic (unstable signal)
Code
SPN 4334 FMI 2
Severity
Warning
Applies to
Check OEM application
Can I drive?
Driving suitability is not established by this code alone.
Common Symptoms
- SCR/DEF warnings
- Pressure readings jump around
- Intermittent inducement risk
Likely Causes
- Pressure sensor connection issue
- Air in DEF system
- Pump struggling or sensor failing
Common Fixes
- Check connector and harness for intermittent contact
- Prime/bleed DEF system if applicable
- Verify pump operation and pressure stability
Full technical sections↓
What does SPN 4334 FMI 2 mean?
Back to top ↑DEF dosing pressure data erratic (unstable signal)
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