Hyundai R305LVS Fault Code 195: Complete Diagnostic Guide

What is Hyundai R305LVS Fault Code 195?

Fault Code 195 on the Hyundai R305LVS excavator indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition. 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 above 4.8-4.9 volts.

The ECT sensor is critical for this excavator's engine management system because it directly influences fuel injection timing, idle speed control, and engine protection protocols. When this sensor circuit fails, the ECM cannot accurately monitor engine operating temperature, potentially leading to inefficient combustion, increased emissions, and inadequate engine protection against overheating conditions on jobsites.

Common Symptoms

When Code 195 is active on your R305LVS, operators typically experience:

• Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated on the instrument cluster
• Hard starting conditions, especially when the engine is cold, due to incorrect fuel enrichment
• Rough idle or irregular engine RPM fluctuations during warm-up periods
• ECM defaulting to a failsafe coolant temperature (usually around 80°C/176°F), causing the engine to run as if always at operating temperature
• Reduced engine performance or potential derate mode activation in severe cases to protect engine components

Potential Causes

The most common technical failures triggering Code 195 in used R305LVS excavators include:

• Open circuit in the ECT sensor wiring harness, frequently caused by wire chafing against the engine block or frame rails near the thermostat housing
• Failed Engine Coolant Temperature sensor with internal open circuit (common after 5,000-8,000 operating hours)
• Corroded or damaged sensor connector pins exposed to coolant leaks or moisture infiltration at the connection point
• Broken or frayed ground wire for the sensor circuit, particularly at chassis ground points that experience vibration
• ECM internal fault (rare, but possible in high-hour machines with previous electrical issues or voltage spikes)

How to Troubleshoot and Fix Code 195

Step 1: Visual Inspection Begin with a thorough visual examination of the ECT sensor located near the thermostat housing on the engine block. Inspect the sensor connector for corrosion, coolant contamination, or bent pins. On used excavators, carefully trace the wiring harness from the sensor to the ECM, checking for obvious damage, melted insulation, or harness rub points against moving components or hot exhaust surfaces.

Step 2: Electrical Testing Disconnect the ECT sensor connector and use a digital multimeter (DMM) to measure resistance across the sensor terminals. At room temperature (20°C/68°F), resistance should typically read 2,000-3,000 ohms (consult your service manual for exact specifications). Next, check for continuity in the wiring harness between the sensor connector and the ECM pins. Measure voltage at the harness connector with ignition on, engine off—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Component Replacement and Verification If sensor resistance is out of specification or the circuit shows an open condition, replace the ECT sensor with a genuine Hyundai or OEM-equivalent part. For used machinery, always apply dielectric grease to connector pins before reassembly to prevent future corrosion. After installation, clear the fault code using Hyundai diagnostic software or a compatible scan tool, then monitor coolant temperature readings during a complete warm-up cycle to verify proper operation.

Critical Note for Used Equipment: Before replacing the sensor, verify that coolant level is adequate and inspect for air pockets in the cooling system, as these can cause erratic temperature readings that may falsely trigger this code.

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Disclaimer: This guide provides general diagnostic information for Code 195. Always consult the official Hyundai service manual for your specific machine serial number and consider professional diagnosis for complex electrical issues or if you're uncomfortable performing these procedures.