Mitsubishi Fault Code

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P1298

Black Smoke / Heavy Turbo Lag

Variant 1

System

Air Intake / Turbo

Symptom

Black Smoke / Heavy Turbo Lag

Diagnosis & fix steps

LOGIC: Variable Geometry Turbocharger (VGT) Vane Position Control Error. ACTION: Inspect vacuum actuator lines for splits/dry rot. Check mechanical VGT sector arm on the turbo hot housing for physical carbon seizing. Test boost control solenoid duty cycle.

Red Seal field insights

Soot Seizing: Low-speed lugging and high-ash regional fuels cause extreme carbon crust buildup around the internal sliding nozzle vanes, physically locking the variable geometry mechanism.

Variant 2

System

Not specified

Symptom

Engine overheats; AC stops working; Fan won't engage.

Diagnosis & fix steps

VGT High Pressure (Overboost) / Protection Mode. LOGIC: The ECU has detected excessive boost and has cut fuel to protect the engine. ACTION: 1. Check VGT solenoid for sticking. 2. Check for carbon buildup in the turbo vanes. 3. Check Boost sensor for "drift" (reading too high). FIX: Replace VGT solenoid or clean/replace Turbocharger.

Red Seal field insights

This often happens when the machine is under heavy load. If the VGT vanes stick "closed," the boost will skyrocket, and the ECU will kill the power to save the head gasket.

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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