What is Hitachi ZX210H-5G Fault Code 13304-2?

Fault Code 13304-2 on the Hitachi ZX210H-5G indicates a deviation from normal in the engine coolant temperature sensor circuit, specifically detecting an abnormal voltage signal or intermittent connection. This Diagnostic Trouble Code (DTC) is triggered when the Engine Control Module (ECM) receives voltage readings outside the expected range from the coolant temperature sensor, typically caused by circuit malfunctions rather than actual overheating conditions.

This code is critical for the ZX210H-5G's performance because the ECM relies on accurate coolant temperature data to optimize fuel injection timing, engine protection protocols, and emission control strategies. When this sensor circuit fails, the engine may operate in a default "limp mode" with reduced power output, potentially causing productivity losses and accelerated engine wear due to improper fuel-air mixture calibration.

Common Symptoms

• Engine warning light illuminated on the instrument cluster with reduced engine power
• Difficulty starting the engine, especially during cold weather conditions
• Erratic temperature gauge readings that fluctuate unexpectedly or remain at maximum/minimum positions
• Excessive black smoke from the exhaust due to incorrect fuel enrichment
• Activated derate mode limiting engine RPM to approximately 1,500-1,800 range

Potential Causes

The most common technical causes for Code 13304-2 on used ZX210H-5G excavators include:

• Corroded or damaged wiring harness connections at the coolant temperature sensor, particularly where the harness routes near the engine block and experiences heat cycling
• Failed coolant temperature sensor due to internal resistance drift (common after 5,000+ operating hours)
• Chafed wiring at known rub points near the fuel injection pump mounting bracket
• Contaminated connector pins from coolant leaks or moisture intrusion in the ECM harness
• ECM internal fault (rare, but possible in high-hour machines with electrical system stress)

How to Troubleshoot and Fix Code 13304-2

Step 1: Visual Inspection Inspect the coolant temperature sensor and its wiring harness for obvious damage, corrosion, or coolant contamination. On used excavators, pay special attention to connector integrity—green corrosion on pins is common. Disconnect the sensor connector and clean with electrical contact cleaner.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the sensor's resistance. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms. Compare readings against Hitachi's specification chart. If resistance is infinite or near zero, replace the sensor.

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

Step 4: Harness Continuity Test Check for continuity between the sensor connector and ECM pins (consult service manual for pin identification). Resistance should be less than 1 ohm. Higher readings indicate corroded connections or broken wires—common in the harness section near the alternator on ZX210H-5G models.

Step 5: Clear Code and Test After repairs, clear the fault code using Hitachi Dr.EX diagnostic software or compatible scan tool. Operate the machine through temperature cycles to verify the fix.

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