What is Hyundai HX220 NL EPFC Fault Code 195 (111-3)?

Fault Code 195 (111-3) on the Hyundai HX220 NL EPFC indicates an Engine Coolant Temperature (ECT) Sensor Circuit High Voltage condition. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally high voltage signal from the coolant temperature sensor, typically above 4.8-4.9 volts, which the system interprets as an implausible reading.

The ECT sensor is critical for the HX220's engine management system, as it provides real-time coolant temperature data that directly affects fuel injection timing, engine warm-up protocols, and cooling fan activation. When this code activates, the ECM enters a fail-safe mode using default temperature values, which can significantly impact engine performance and fuel efficiency on used machines already experiencing wear.

Common Symptoms

• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Engine runs in cold-start enrichment mode continuously, resulting in excessive black smoke and poor fuel economy
• Cooling fan runs constantly at high speed regardless of actual engine temperature
• Difficulty starting when the engine is warm, as the ECM misinterprets temperature conditions
• Possible engine derating or reduced power output to protect components from perceived overheating

Potential Causes

The most common causes of Code 195 (111-3) on used HX220 excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing near the engine block mounting points
• Failed ECT sensor with internal open circuit (common after 5,000+ operating hours)
• Corroded or loose connector at the sensor or ECM interface due to coolant leaks or environmental exposure
• Damaged wiring harness from rodent activity or improper previous repairs
• Rare: ECM internal fault affecting the 5-volt reference circuit (verify other sensors first)

How to Troubleshoot and Fix Code 195 (111-3)

Step 1: Visual Inspection Locate the ECT sensor on the engine block (typically near the thermostat housing). Inspect the sensor connector and wiring harness for visible damage, corrosion, coolant contamination, or loose connections. On used excavators, pay special attention to harness routing where friction against engine components commonly occurs.

Step 2: Electrical Testing Disconnect the ECT sensor connector. Using a digital multimeter, measure resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms. If the reading shows infinite resistance (open circuit), the sensor has failed and requires replacement.

Step 3: Circuit Verification With the sensor disconnected, measure voltage at the harness connector (ECM side). You should see approximately 5 volts on the signal wire with ignition on. If voltage reads above 4.9 volts constantly, inspect wiring for breaks. Check ground continuity on the sensor ground wire—resistance to chassis ground should be less than 1 ohm.

Step 4: Sensor Replacement and Verification Replace the ECT sensor using OEM or equivalent quality parts (aftermarket sensors often fail prematurely on diesel applications). Apply thread sealant, torque to specifications (typically 15-20 ft-lbs), and clear codes using Hyundai diagnostic software or compatible scan tool. Monitor live data to confirm proper temperature readings (gradually rising from ambient to 180-200°F).

For used excavators: Before replacing the ECM, thoroughly inspect all connectors for "green corrosion" inside terminals and verify harness continuity from sensor to ECM pin-by-pin, as wiring issues account for 70% of high-voltage ECT codes.

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