JCB Fault Code

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P0122

Engine Defaults to Low Idle / Throttle Dial Dead

System

Throttle / Engine

Symptom

Engine Defaults to Low Idle / Throttle Dial Dead

Diagnosis & fix steps

LOGIC: Rotary Engine Throttle Position Potentiometer Circuit Low. ACTION: Remove rotary throttle dial from side console. Measure resistance across pins 1 and 3 (spec: ~5kΩ) and check center wiper sweep (0.5V to 4.5V); replace worn carbon-track pot.

Red Seal field insights

Carbon Track Wear: Fine construction dust penetrates the non-sealed rotary potentiometer body, grinding away the resistive carbon strip at common mid-throttle operating positions.

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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