Isuzu Fault Code

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P1421

Frequent Regens / DPF Face Loading

System

Emissions / DPF

Symptom

Frequent Regens / DPF Face Loading

Diagnosis & fix steps

LOGIC: Exhaust DPF Regeneration Exhaust Glow Plug Failure. ACTION: Remove the specialized diesel exhaust fluid vaporizer injector plug. Test internal heating element coil resistance for an open path. Clean heavy soot crust off the nozzle tip.

Red Seal field insights

Thermal Chemistry: This auxiliary plug vaporizes diesel fuel sprayed upstream of the DOC during a regen; a dead heater stalls the thermal climb needed to scorch soot.

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.

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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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