What is Komatsu PC110-8M0 Fault Code CA145?

Fault Code CA145 on the Komatsu PC110-8M0 indicates a malfunction in the hydraulic oil temperature sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition. This code is generated when the machine's controller (ECM) receives a voltage reading from the hydraulic oil temperature sensor that exceeds the normal operational range, typically above 4.8-4.9 volts.

The hydraulic oil temperature sensor plays a critical role in protecting the PC110-8M0's hydraulic system by monitoring oil temperature and preventing overheating damage to pumps, motors, and seals. When this sensor circuit fails, the ECM cannot accurately assess hydraulic system conditions, potentially leading to inadequate protection protocols and reduced machine performance.

Common Symptoms

When CA145 is active on your Komatsu PC110-8M0, you may experience:

• Warning light illumination on the instrument panel, often accompanied by an audible alarm
• Hydraulic system derate where the machine limits pump output to protect components from potential overheating
• Inaccurate or frozen temperature gauge readings on the monitor display showing either maximum temperature or no reading
• Engine auto-shutdown in some cases if the fault persists, as a protective measure
• Stored fault code in ECM memory even after the immediate issue resolves

Potential Causes

The most common technical reasons for CA145 on used PC110-8M0 excavators include:

• Open circuit in sensor wiring harness, particularly where cables run near moving hydraulic lines or sharp chassis edges
• Failed hydraulic oil temperature sensor due to internal element breakage or moisture intrusion (common after 4,000+ operating hours)
• Corroded or loose connector pins at the sensor plug, especially on machines operated in coastal or high-humidity environments
• Damaged ECM input circuit, though less common, can occur from previous electrical work or power surges
• Harness chafing at known wear points near the hydraulic tank mounting bracket where cable ties deteriorate over time

How to Troubleshoot and Fix Code CA145

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor (mounted on the hydraulic tank). Inspect the wiring harness from sensor to ECM for obvious damage, abraded insulation, or oil contamination. Check the connector for corrosion, bent pins, or moisture—common issues in used excavators.

Step 2: Electrical Testing Disconnect the sensor connector. Using a digital multimeter, measure resistance across the sensor terminals. A properly functioning sensor should read approximately 200-500 ohms at ambient temperature (consult Komatsu specifications). An infinite reading indicates sensor failure or open circuit.

Step 3: Voltage Check With ignition on and sensor disconnected, measure voltage at the harness-side connector. You should see approximately 5 volts reference voltage from the ECM. No voltage indicates a harness break or ECM issue.

Step 4: Circuit Continuity Check continuity between the sensor connector and ECM pins (refer to PC110-8M0 wiring diagram). For used machines, pay special attention to harness routing near hydraulic cooler lines where vibration causes conductor fatigue.

Step 5: Sensor Replacement If sensor tests fail, replace with a genuine Komatsu temperature sensor (Part # 7861-93-3520 or equivalent). Clear codes using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then test operate the machine.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues.