Hyundai HX220 NL EPFC Fault Code 3317 (3242-3): Meaning and Fix

What is Hyundai HX220 NL EPFC Fault Code 3317 (3242-3)?

Fault Code 3317 (3242-3) indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormal voltage signal or open circuit condition in the ECM (Engine Control Module) monitoring system.

This code triggers when the ECM detects that the coolant temperature sensor is sending voltage readings outside the expected range—typically either too high (open circuit) or erratic. The coolant temperature sensor is critical for the HX220 NL's EPFC (Electronic Pump Flow Control) system because it directly influences fuel injection timing, hydraulic pump output, and engine protection protocols. When this sensor fails, the machine may enter a derate mode to prevent overheating damage, significantly reducing productivity on job sites.

Common Symptoms

• Engine warning light illuminated on the instrument cluster, often accompanied by a coolant temperature gauge reading abnormally high or low
• Reduced engine power or hydraulic system performance as the ECM limits output to protect components
• Hard starting or rough idle, especially when the engine is cold
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Intermittent stalling or hesitation during operation, particularly under load

Potential Causes

The most common technical causes for Code 3317 in used HX220 NL excavators include:

• Coolant temperature sensor failure due to internal element degradation (common after 5,000+ operating hours)
• Wiring harness damage near the sensor connector, particularly where the harness routes along the engine block and experiences heat cycling and vibration
• Corroded or loose connector pins at the sensor plug—moisture intrusion is frequent in this location on older machines
• ECM internal fault affecting the sensor input circuit (less common but possible in high-hour units)
• Damaged sensor mounting threads causing poor thermal contact with the coolant jacket

How to Troubleshoot and Fix Code 3317 (3242-3)

Step 1: Visual Inspection
Begin by locating the coolant temperature sensor on the engine block (typically near the thermostat housing). Inspect the wiring harness for obvious damage—look for chafing against brackets, melted insulation from exhaust heat, or rodent damage. Check the connector for corrosion, bent pins, or moisture. On used excavators, this connector often shows green corrosion due to coolant mist exposure.

Step 2: Electrical Testing
Disconnect the sensor and use a digital multimeter to measure resistance across the sensor terminals. At room temperature (20°C/68°F), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). If the reading is infinite (open circuit) or near zero, the sensor has failed. Next, check the harness side: measure voltage at the connector with the ignition on—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Sensor Replacement and Verification
If testing confirms sensor failure, replace it with an OEM or equivalent quality sensor. Apply a small amount of heat-transfer compound to the threads before installation to ensure accurate temperature reading. After replacement, clear the fault code using Hyundai diagnostic software (Hi-Scan Pro or equivalent) and monitor for code recurrence. If the code returns immediately, suspect ECM issues or a short circuit in the harness requiring professional tracing.

Disclaimer: This guide provides general troubleshooting steps. For complex electrical diagnostics or ECM replacement, consult a certified Hyundai heavy equipment technician or authorized service center.