Komatsu PC850SE-8R Fault Code E-22: Complete Diagnostic Guide

What is Komatsu PC850SE-8R Fault Code E-22?

Fault Code E-22 indicates a malfunction in the hydraulic oil temperature sensor circuit or an abnormal hydraulic oil temperature reading. This code is triggered when the Electronic Control Module (ECM) detects either an open circuit, short circuit, or out-of-range temperature values from the hydraulic oil temperature sensor.

The hydraulic oil temperature sensor is critical for the PC850SE-8R's performance management system. It monitors the operating temperature of the hydraulic fluid, allowing the ECM to adjust pump output, implement protective derating, and prevent catastrophic damage to hydraulic components. When this sensor fails or provides incorrect data, the machine cannot properly regulate hydraulic system performance, potentially leading to overheating or inefficient operation.

Common Symptoms

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

• Warning light illuminated on the instrument panel, often accompanied by an audible alarm
• Reduced hydraulic performance or sluggish attachment response, especially during warm-up
• Automatic engine derate or power reduction mode to protect hydraulic components
• Inaccurate or erratic hydraulic temperature gauge readings on the monitor display
• Machine may enter limp mode preventing operation until the issue is addressed

Potential Causes

The most common technical causes for E-22 on used PC850SE-8R excavators include:

• Faulty hydraulic oil temperature sensor due to age-related degradation or contamination exposure
• Damaged wiring harness or connector corrosion, particularly at routing points near the hydraulic tank where vibration and heat exposure are highest
• Open or short circuit in the sensor wiring, often caused by harness chafing against frame components
• ECM internal fault or corrupted calibration data (less common)
• Contaminated hydraulic oil causing sensor element fouling
• Poor ground connections at the sensor mounting location

How to Troubleshoot and Fix Code E-22

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor (typically mounted on the hydraulic tank). Inspect the wiring harness for obvious damage, abrasion, or oil contamination. Check the connector for corrosion, bent pins, or moisture intrusion—common issues in used excavators operating in harsh environments.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. Compare readings against Komatsu specifications (typically 200-400 ohms at 20°C, varying with temperature). Check for continuity in the wiring from sensor to ECM connector. Measure supply voltage (usually 5V reference) at the sensor connector with ignition on.

Step 3: Component Testing and Replacement If resistance values are out of specification or wiring shows damage, replace the faulty component. For used excavators, always inspect harness routing for wear points and secure with proper clamps. Clean all connector terminals with electrical contact cleaner before reassembly. Clear the fault code using Komatsu diagnostic software and perform a test cycle to verify repair.

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