Komatsu PC800-8R Fault Code E-22: Complete Diagnostic Guide

What is Komatsu PC800-8R Fault Code E-22?

Fault Code E-22 on the Komatsu PC800-8R indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the Engine Control Module (ECM). This code specifically relates to the temperature monitoring system that protects the engine from overheating damage.

The coolant temperature sensor sends voltage signals to the ECM, which uses this data to regulate fuel injection timing, engine speed, and activate warning systems. On the PC800-8R's SAA6D170E-5 engine, maintaining accurate temperature readings is critical for preventing catastrophic engine damage and ensuring optimal hydraulic system performance. When E-22 triggers, the ECM may enter a protective derate mode to prevent overheating.

Common Symptoms

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

• Engine warning light illuminated on the monitor panel, often accompanied by an audible alarm
• Reduced engine power or automatic derate mode limiting machine performance
• Inaccurate temperature gauge readings showing extremely high, low, or erratic temperatures
• Difficulty starting the engine, particularly in cold conditions
• Increased fan operation as the ECM attempts to compensate for perceived high temperatures

Potential Causes

The most common technical causes for E-22 on used PC800-8R excavators include:

• Failed coolant temperature sensor due to age-related degradation or thermal cycling damage
• Damaged wiring harness or corroded connectors, particularly at rub points near the engine block
• Open or short circuit in the sensor signal wire between the sensor and ECM
• Corroded sensor terminals from coolant leaks or moisture intrusion in the connector
• ECM internal fault (less common) affecting the temperature input circuit
• Low coolant level causing actual overheating and triggering legitimate high-temperature warnings

How to Troubleshoot and Fix Code E-22

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block (typically near the thermostat housing). Check for coolant leaks, damaged wiring, and corroded connectors. On used excavators, examine harness routing for wear points where cables contact metal surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. At 20°C (68°F), resistance should typically read 2,000-3,000 ohms (consult service manual for exact specifications). Check for continuity in the wiring harness from sensor to ECM connector.

Step 3: Voltage Signal Check With the sensor connected and ignition on (engine off), measure reference voltage at the sensor connector—should read approximately 5 volts. If voltage is absent, suspect ECM or harness issues.

Step 4: Connector Service Clean all connector terminals with electrical contact cleaner and apply dielectric grease. Corrosion is extremely common in used machines and often resolves intermittent codes.

Step 5: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu coolant temperature sensor. Clear codes using Komatsu diagnostic software (KOMTRAX) and verify repair through operational testing.

---

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 or repairs.