What is Hyundai R805LC-7 Fault Code 1244-6?

Fault Code 1244-6 on the Hyundai R805LC-7 excavator indicates an Engine Water Temperature (EWT) Sensor Circuit voltage is below the normal operating range (moderately severe condition). This Diagnostic Trouble Code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally low voltage signal from the coolant temperature sensor, typically below 0.2 volts. The sensor monitors engine coolant temperature and sends critical data to the ECM for proper fuel injection timing, idle speed control, and overheat protection.

This code is particularly critical for the R805LC-7's Cummins QSX15 engine because incorrect temperature readings can cause improper fuel-air mixture, delayed warning systems, and potential catastrophic engine damage. The "6" severity modifier indicates a moderately severe electrical fault requiring prompt attention to prevent engine performance degradation.

Common Symptoms

• Check Engine Light or malfunction warning lamp illuminated on the instrument cluster
• Inaccurate temperature gauge readings, often showing extremely cold temperatures even when the engine is warm
• Hard starting conditions or extended cranking time, especially in cold weather
• Rough idle or irregular engine RPM due to incorrect fuel mapping
• Poor fuel economy and black smoke from exhaust due to overly rich fuel mixture

Potential Causes

The most common technical causes for Code 1244-6 on used R805LC-7 excavators include:

• Damaged or shorted coolant temperature sensor wiring harness, particularly where the harness routes near the engine block or frame rails (known wear point on this model)
• Failed Engine Water Temperature Sensor with internal short circuit to ground
• Corroded or loose connector pins at the sensor plug or ECM connection points
• Chafed wiring from vibration damage or improper previous repairs rubbing against engine components
• ECM internal fault (less common, but possible in high-hour machines)
• Ground circuit issues affecting sensor signal return path

How to Troubleshoot and Fix Code 1244-6

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor and its wiring harness. The sensor is typically located on the engine block near the thermostat housing. Check for obvious damage, corrosion on the two-pin connector, or fluid contamination. On used excavators, examine harness routing for abrasion points where wires contact metal edges.

Step 2: Electrical Testing Using a digital multimeter (DMM), disconnect the sensor connector and measure resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should be approximately 2,000-3,000 ohms (consult service manual for exact specifications). Also check for continuity between sensor pins and ground—there should be infinite resistance (no short to ground).

Step 3: Circuit Voltage Check With ignition ON and sensor disconnected, measure voltage at the harness connector. You should see approximately 5 volts on the signal wire (reference voltage from ECM). If voltage is absent or incorrect, trace wiring back to the ECM connector checking for breaks or shorts.

Step 4: Repair or Replace If the sensor tests faulty, replace with OEM or quality aftermarket unit. If wiring is damaged, repair using proper gauge wire and heat-shrink connections—avoid electrical tape in engine compartments. Clear codes using Hyundai Hi-MATE diagnostic software or compatible scan tool and perform test run.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the Hyundai R805LC-7 service manual for exact specifications and procedures. For complex electrical issues or if unfamiliar with diagnostic equipment, seek assistance from a certified Hyundai or Cummins diesel technician.