Komatsu PC70-8 Fault Code E-22: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code E-22?

Fault Code E-22 on the Komatsu PC70-8 indicates a malfunction in the hydraulic oil temperature sensor circuit. This code triggers when the Engine Control Module (ECM) detects an abnormal voltage signal from the temperature sensor monitoring the hydraulic oil system.

The hydraulic oil temperature sensor plays a critical role in protecting the PC70-8's hydraulic system by monitoring operating temperatures. When oil temperatures exceed safe limits or the sensor circuit fails, the ECM logs this fault to prevent catastrophic damage to hydraulic components, pumps, and seals. For compact excavators like the PC70-8, maintaining proper hydraulic oil temperature is essential for optimal performance and component longevity.

Common Symptoms

When Code E-22 is active, operators typically experience:

• Warning light illuminated on the instrument panel (typically a hydraulic system indicator)
• Erratic or inaccurate hydraulic oil temperature readings on the display
• Reduced hydraulic performance or machine entering a derated operating mode
• Intermittent loss of hydraulic functions during operation
• Audible warning alarm in some cases when temperature thresholds are exceeded

Potential Causes

The most common technical causes for E-22 on used PC70-8 excavators include:

• Faulty hydraulic oil temperature sensor due to age-related degradation or contamination
• Damaged or corroded wiring harness connections at the sensor plug
• Chafed wires along the harness routing near the hydraulic tank (common wear point on this model)
• Poor ground connection at the sensor mounting location
• ECM internal fault (rare, but possible in high-hour machines)
• Contaminated hydraulic oil causing sensor element failure

How to Troubleshoot and Fix Code E-22

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor on the hydraulic tank. Inspect the sensor connector for corrosion, oil contamination, or damaged pins. On used excavators, check the wiring harness for rub points against the frame or hydraulic lines—a common failure point on the PC70-8.

Step 2: Electrical Testing Using a digital multimeter, check sensor resistance. The sensor should typically read 200-400 ohms at room temperature (consult your service manual for exact specifications). Test voltage supply at the connector with the key on—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Circuit Verification Disconnect the sensor and measure continuity between the sensor ground wire and chassis ground. Check for short circuits between signal and ground wires. Inspect for harness corrosion inside protective loom, especially near hydraulic tank mounting brackets.

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu part. Clean all connector terminals with electrical contact cleaner before reconnection. Clear the fault code using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool and verify repair.

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