XCMG XE15 Mini Excavator Fault Code 145: Meaning, Symptoms & Fix

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What is XCMG XE15 Fault Code 145?

XCMG XE15 Fault Code 145 indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor circuit — specifically, the signal voltage has fallen outside the acceptable operating range, typically detected as an out-of-range low or open circuit condition by the Engine Control Module (ECM).

The ECT sensor is a critical input device that feeds real-time coolant temperature data to the ECM, allowing it to regulate fuel delivery, injection timing, and engine protection strategies. On the XCMG XE15 — a compact mini excavator commonly powered by a Yanmar or Kubota-sourced diesel engine — this sensor plays a direct role in preventing overheating and ensuring correct cold-start enrichment cycles.

When the ECM receives a signal that falls below the minimum threshold (typically under 0.2V), it logs Fault Code 145 and may activate protective engine management responses. Ignoring this code on a used machine can mask genuine overheating events, leading to costly engine damage.

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Common Symptoms

When Fault Code 145 is active on the XCMG XE15, operators typically report:

• Warning light illuminated on the instrument cluster (temperature or engine warning indicator)
• Erratic or fixed temperature gauge readings, often pegged at cold or showing no movement
• Poor cold-start performance — rough idle, excessive white smoke, or prolonged warm-up behavior
• Possible engine derating — reduced power output as the ECM enters a protective limp mode
• Automatic fan activation running continuously as the ECM defaults to worst-case cooling assumptions

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Potential Causes

The following are the most common root causes for Fault Code 145, particularly on used or older XCMG XE15 units:

• Failed ECT sensor — internal resistance drift or open circuit due to age and heat cycling
• Corroded or damaged sensor connector — moisture ingress is extremely common on used mini excavators stored outdoors
• Chafed or broken wiring harness — the harness routing near the engine block is a known friction point on compact excavators
• Poor ground connection at the sensor or ECM ground circuit
• ECM pin corrosion — especially on machines with prior water damage or improper pressure washing

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How to Troubleshoot and Fix Code 145

Step 1 — Visual Inspection First Begin with a thorough inspection of the ECT sensor, its connector, and the associated wiring harness. On used excavators, look specifically for harness abrasion against metal edges, cracked insulation, and green or white corrosion inside the connector pins. Never skip this step — replacing parts without checking harness condition is a common and costly mistake.

Step 2 — Sensor Resistance Test Disconnect the ECT sensor connector. Using a digital multimeter, measure the sensor's resistance between its two terminals. A healthy NTC (Negative Temperature Coefficient) sensor should read approximately 2,000–3,000 ohms at ambient temperature (20°C/68°F), decreasing as temperature rises. A reading of infinite resistance (OL) confirms an open circuit and a failed sensor.

Step 3 — Circuit Voltage & Continuity Check With the ignition ON and the sensor disconnected, measure the reference voltage at the harness connector. You should see approximately 5V DC from the ECM reference wire. Then perform a continuity test on the signal wire from the connector back to the ECM pin to rule out a broken circuit. Use XCMG-compatible diagnostic software (such as XCMG SmartDiag or a compatible J1939 OBD scanner) to confirm the live fault and clear codes after repair.

Step 4 — Connector & Ground Cleaning Apply electrical contact cleaner and use a pin tool to gently restore connector pin tension. Verify the sensor ground circuit reads less than 0.1 ohm resistance back to chassis ground. A high resistance ground is frequently overlooked on used machines and can mimic a sensor failure.

Step 5 — Replace the ECT Sensor if Required If the sensor fails the resistance test, replace it with an OEM-specification unit. After installation, clear the fault code using diagnostic software, run the engine through a full warm-up cycle, and confirm the code does not return.

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Professional Disclaimer: The diagnostic procedures outlined in this guide are intended for qualified heavy diesel mechanics and experienced equipment technicians. Working on engine management systems involves electrical components and hot engine surfaces that can cause serious injury if mishandled. Always consult the official XCMG XE15 service manual and follow all relevant safety protocols. If you are uncertain about any step, contact an authorized XCMG service dealer or a certified heavy equipment technician before proceeding.