Global SCR Fault Code

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SPN 3364 FMI 2 / 17

Engine derate; "DEF Symbol" flashing; Machine may eventually lock into 5 MPH or Idle-only.

System

Not specified

Symptom

Engine derate; "DEF Symbol" flashing; Machine may eventually lock into 5 MPH or Idle-only.

Diagnosis & fix steps

DEF Quality / Concentration Low. LOGIC: The DEF Quality sensor (ultrasonic) detects the urea concentration is outside the 32.5% +/- 1.5% range. ACTION: 1. Test DEF with a refractometer (Target 32.5%). 2. Check for "blue" dye or diesel smell in the DEF tank. 3. Drain and flush tank if contaminated. FIX: Drain and refill with fresh ISO 22241 certified DEF; replace DEF Quality Sensor if reading stays static.

Red Seal field insights

Many technicians overlook "Old" DEF. In hot climates, the water evaporates and the urea concentration climbs. If your refractometer shows 35%+, the machine will trip this code. Simply adding distilled water can sometimes save the batch.

Same code keeps coming back?

That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.

Book an uptime review

Read before you touch anything

  • This is general reference information, not a repair manual. It is for trained, qualified technicians.
  • Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
  • Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
  • You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
  • Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.

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