XCMG B3.9-5.9-C8.3 CM2150 Fault Code 110-2: Complete Diagnostic Guide

What is XCMG B3.9-5.9-C8.3 CM2150 Fault Code 110-2?

Fault Code 110-2 indicates an "Engine Coolant Temperature Sensor Circuit - Data Erratic, Intermittent, or Incorrect" condition in the Cummins CM2150 electronic control system. This code triggers when the Engine Control Module (ECM) detects inconsistent or implausible voltage signals from the coolant temperature sensor, typically caused by values fluctuating outside normal operating parameters or showing rapid, unexplained changes.

The coolant temperature sensor is critical for the CM2150's fuel injection timing, engine protection strategies, and emission control functions. When this sensor provides unreliable data, the ECM cannot properly manage engine temperature, potentially leading to performance issues, increased fuel consumption, or engine damage if the true temperature exceeds safe limits. For used XCMG excavators with Cummins power, this fault often stems from sensor degradation or harness wear common in high-hour machines.

Common Symptoms

• Check Engine Light illuminated on the dashboard with possible amber warning indicator
• Engine derate mode activated, limiting power output to 75% or less to protect components
• Erratic cooling fan operation, cycling on/off unexpectedly or running continuously
• Difficulty starting when the engine is cold, with extended cranking periods
• Rough idle or hesitation during warm-up cycles due to incorrect fuel mapping

Potential Causes

The 110-2 code typically results from these specific issues in used excavators:

• Corroded or loose sensor connector at the coolant temperature sensor, common on machines operating in wet or corrosive environments
• Damaged wiring harness between the sensor and ECM, particularly at rub points near the engine block or frame rails
• Failing coolant temperature sensor with internal resistance drift, typical after 5,000+ operating hours
• Intermittent short to ground in the signal wire caused by harness chafing against sharp edges
• ECM internal circuit degradation (rare, but possible in high-vibration applications)
• Poor engine ground connections causing voltage reference issues across the sensor circuit

How to Troubleshoot and Fix Code 110-2

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor connector located on the engine block's coolant passage. Disconnect the two-pin connector and check for corrosion, bent pins, or moisture intrusion. On used excavators, verify the wiring harness routing for wear points where insulation may be damaged from rubbing against the engine or frame.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the sensor's resistance across its terminals. At 68°F (20°C), resistance should read approximately 3,000-3,500 ohms; at 194°F (90°C), expect 200-300 ohms. Values significantly outside this range indicate sensor failure requiring replacement with genuine Cummins parts (Part #4921744 or equivalent).

Step 3: Circuit Voltage Testing With the sensor disconnected and ignition on (engine off), measure voltage at the ECM-side harness connector. The signal wire should show approximately 5 volts from the ECM's reference voltage. If voltage is absent or significantly different, trace the harness for breaks or shorts, paying special attention to areas where the harness passes through bulkheads or near hydraulic lines.

Step 4: Signal Wire Integrity Check Perform a voltage drop test on the signal and ground wires between the sensor and ECM while wiggling the harness. Intermittent voltage changes indicate damaged insulation or internal wire breaks common in high-vibration environments. Replace damaged harness sections rather than attempting repairs with electrical tape.

Step 5: Clear Code and Monitor After repairs, clear the fault code using Cummins INSITE diagnostic software or an appropriate scan tool. Operate the machine through a complete heat cycle, monitoring live coolant temperature data for erratic readings or sudden jumps that would indicate remaining circuit issues.

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Disclaimer: This guide provides general diagnostic procedures for experienced technicians. Always consult the official XCMG and Cummins service manuals for your specific machine serial number. If you lack proper diagnostic tools or experience with high-voltage electrical systems, seek assistance from a certified Cummins or XCMG service center.