What does Isuzu fault code P0673 mean?

Q: What does Isuzu fault code P0673 mean?

P0673 indicates: Hard Cold Start / White Smoke / Glow Plug Light Flashing Fix: LOGIC: Cylinder 3 Glow Plug Circuit Open or High Resistance. ACTION: Disconnect the harness lead from the Cylinder 3 glow plug. Measure internal resistance between the plug terminal stud and engine cylinder head ground (spec: ~0.5–1.5Ω at 20°C). If open (>10kΩ), soak the threads with penetrating oil, warm the head slightly if possible, and extract using a torque-limiting wrench to avoid shearing the pencil tip. If the plug measures within spec, load-test the feed wire from the Glow Plug Relay/Control Module for high resistance or terminal fretting.

Isuzu Fault Code

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P0673

Hard Cold Start / White Smoke / Glow Plug Light Flashing

System

Starting / Glow Plugs

Symptom

Hard Cold Start / White Smoke / Glow Plug Light Flashing

Diagnosis & fix steps

LOGIC: Cylinder 3 Glow Plug Circuit Open or High Resistance. ACTION: Disconnect the harness lead from the Cylinder 3 glow plug. Measure internal resistance between the plug terminal stud and engine cylinder head ground (spec: ~0.5–1.5Ω at 20°C). If open (>10kΩ), soak the threads with penetrating oil, warm the head slightly if possible, and extract using a torque-limiting wrench to avoid shearing the pencil tip. If the plug measures within spec, load-test the feed wire from the Glow Plug Relay/Control Module for high resistance or terminal fretting.

Red Seal field insights

Terminal Stud Vibration: The 4HK1 engine uses individual glow plug feeds off the sub-harness rather than a single solid busbar. Engine harmonics often fatigue the small eyelet ring terminal or back off the 8 mm brass securing nut on Cylinder 3, mimicking a burned-out glow plug element.

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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