Caterpillar Fault Code

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SPN 168 FMI 2

Lights flickering; Radio resetting; Random "ghost" codes across different systems; Hard starting.

System

Not specified

Symptom

Lights flickering; Radio resetting; Random "ghost" codes across different systems; Hard starting.

Diagnosis & fix steps

System Voltage Intermittent LOGIC: Battery voltage is "noisy" or dropping below 9V momentarily. ACTION: Perform a load test on batteries. Check the "Clean Machine Ground" (usually a small wire directly to the battery negative). Inspect alternator belt tension. FIX: Clean/tighten battery terminals; replace batteries or alternator.

Red Seal field insights

On CAT machines, 90% of intermittent electrical issues are caused by a loose or corroded main ground stud on the frame. Clean it down to shiny metal.

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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