Komatsu PC220-10 Fault Code H-13: Complete Diagnostic Guide

What is Komatsu PC220-10 Fault Code H-13?

Fault Code H-13 on the Komatsu PC220-10 excavator indicates a malfunction in the hydraulic oil temperature sensor circuit, specifically detecting an abnormal voltage signal from the temperature sensor located in the hydraulic tank.

This code triggers when the Electronic Control Module (ECM) receives either an excessively high or low voltage reading from the hydraulic oil temperature sensor, indicating the sensor cannot accurately monitor oil temperature. For the PC220-10's advanced hydraulic system, precise temperature monitoring is critical because it protects expensive hydraulic components from thermal damage and ensures optimal viscosity for system performance. When this sensor fails, the machine cannot properly regulate hydraulic oil cooling or warn operators of overheating conditions.

Common Symptoms

When Code H-13 activates on your PC220-10, you'll typically experience:

• Hydraulic temperature warning light illuminated on the monitor panel, often accompanied by an audible alarm
• Reduced hydraulic performance as the ECM may limit pump output to prevent potential overheating
• Inaccurate or frozen temperature readings displayed on the multi-function monitor (often showing abnormally high or low values)
• Intermittent fault triggering during cold starts or after extended operation, especially in used machines with deteriorated wiring
• Derate mode activation in severe cases, limiting swing speed and boom/arm movements

Potential Causes

The most common technical causes for H-13 on used PC220-10 excavators include:

• Failed hydraulic oil temperature sensor due to internal element degradation (common after 6,000+ operating hours)
• Damaged sensor wiring harness from rubbing against the hydraulic tank or frame members near the left-side tank mounting area
• Corroded or loose electrical connectors at the sensor plug, especially on machines exposed to moisture or coastal environments
• Short circuit or open circuit in the sensor signal wire between the sensor and ECM
• Contaminated sensor probe covered in hydraulic fluid residue, sludge, or metallic debris affecting resistance values
• ECM internal fault (rare) causing incorrect voltage interpretation

How to Troubleshoot and Fix Code H-13

Step 1: Visual Inspection and Connector Check Begin by locating the hydraulic oil temperature sensor on the left side of the hydraulic tank. Disconnect the 2-pin electrical connector and inspect for corrosion, bent pins, or moisture intrusion. Clean contacts with electrical contact cleaner and check for oil contamination indicating a failed sensor seal.

Step 2: Sensor Resistance Testing Using a digital multimeter (DMM), measure the sensor's resistance across its two terminals. At 20°C (68°F), resistance should read approximately 2,000-2,500 Ohms. At 80°C (176°F), expect approximately 300-400 Ohms. Values outside this range or an open circuit (infinite resistance) confirm sensor failure requiring replacement (Komatsu Part #: 7861-93-3320 or equivalent).

Step 3: Wiring Harness Continuity Check Disconnect the sensor and locate the corresponding ECM connector (refer to the PC220-10 electrical schematic). Test continuity from the sensor harness connector to the ECM pin using your multimeter—you should read less than 5 Ohms resistance. Also check for shorts to ground (infinite resistance expected). On used excavators, carefully inspect the harness routing along the tank where insulation commonly wears through from vibration.

Step 4: Signal Voltage Verification With the sensor connected and ignition on (engine off), backprobe the sensor connector and measure voltage. You should see approximately 5V reference voltage on the signal wire. If voltage is absent, trace back to the ECM for potential wiring breaks or ECM issues.

Step 5: Clear Code and Monitor After repairs, use Komatsu diagnostic software (KOMTRAX PLUS) or a compatible scan tool to clear the fault code. Operate the machine through a complete heat cycle, monitoring hydraulic temperatures. The code should not return if repairs were successful.

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Disclaimer: This guide provides general diagnostic procedures for Komatsu PC220-10 excavators. Hydraulic and electrical systems operate under pressure and voltage that can cause injury. Always consult the official Komatsu Service Manual and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with heavy equipment repair procedures.