Pressure, Temperature, and Load-Based Faults in Komatsu Machines
Hydraulic and brake systems in Komatsu equipment operate under constant stress. Whether you’re operating a large dozer or a mining-class haul truck, real-time pressure and temperature feedback is essential for safe and efficient operation. Komatsu’s diagnostic codes provide detailed insights into these systems, helping technicians isolate faults quickly.
This article examines selected pressure and thermal fault codes, highlighting their causes and repair procedures.
Steering and Brake Oil Pressure Monitoring
Code 2201L1 – Right Steering Clutch Oil Pressure 1
This error is reported when the oil pressure in the right steering clutch drops below acceptable levels. It may be caused by:
- Internal clutch wear
- Line restriction
- Sensor degradation
Testing involves comparing sensor readings with actual port pressure and assessing temperature rise during prolonged use.
Code 2302LH – Left Steering Brake Oil Pressure 2
Low oil pressure in the brake circuit can lead to diminished stopping power or uneven braking response. Technicians should:
- Inspect for leaks in the brake actuator circuit
- Confirm hydraulic pump output and pressure drop across lines
- Calibrate or replace the pressure sensor if readings remain erratic
Code 2301NR – Right Steering Brake Thermal Load
This code means the brake is overheating, often due to prolonged operation under load or failure of the brake cooling system. Diagnostic procedures include:
- Verifying brake cooling fan operation
- Checking oil temperature with an infrared gun or via KDT
- Reviewing brake application frequency through operator logs
Hydraulic System Pressure Control
Code 2G42ZG – Accumulator Oil Pressure Reduction (Front)
An oil pressure drop in the front hydraulic accumulator may compromise emergency steering, braking, or suspension. Possible root causes:
- Nitrogen charge depletion
- Accumulator check valve leakage
- Pump flow irregularities
Charge pressure should be checked with a proper gauge. If pressure is below spec, nitrogen recharge or accumulator replacement may be necessary.
Code B@HANS – Hydraulic Oil Overheat
Excessive hydraulic oil temperature can lead to system damage and degraded performance. Triggers include:
- Poor heat exchange efficiency
- Restricted return flow
- High ambient temperatures combined with constant duty cycles
Thermal imaging and direct sensor readings can help isolate hot zones. Radiator fan inspection and hydraulic filter changes are often part of the repair process.
Temperature-Related Sensor Failures
Code CA697 – ECM Internal Temperature Sensor High Error
This indicates the Engine Control Module is overheating, possibly due to location near heat sources or insufficient ventilation. Technicians should:
- Inspect mounting location for air flow
- Check for trapped heat in enclosures
- If internal damage is suspected, the ECM may require replacement
Code CA145 – Coolant Temperature Sensor Low Error
A low signal from the coolant temperature sensor may result in over-fueling, poor regeneration, or false cold-start logic. Checks include:
- Confirming sensor output against a known-good resistance curve
- Inspecting coolant level and flow
- Ensuring correct electrical grounding
Komatsu’s advanced diagnostic coding system provides the backbone for rapid, accurate maintenance in the field. Pressure drops, thermal overloads, or solenoid faults no longer require guesswork—just a structured response using reliable data. With tools like KDT and thorough component testing, even complex faults can be resolved quickly to return the machine to full productivity.
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