What is XCMG General Fault Code 108-2?

XCMG Fault Code 108-2 indicates a Turbocharger Boost Pressure Sensor Circuit Low Voltage condition. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an abnormally low voltage signal from the turbocharger boost pressure sensor, falling below the manufacturer's specified threshold (typically below 0.5V).

This sensor plays a critical role in monitoring intake manifold pressure and allowing the ECM to optimize fuel delivery, timing, and air-fuel ratios. In XCMG excavators, particularly used machines operating in demanding conditions, this code directly impacts engine performance, potentially causing power loss, black smoke, and reduced fuel efficiency. The ECM relies on accurate boost pressure readings to prevent over-fueling or under-fueling scenarios that can damage the engine or turbocharger assembly.

Common Symptoms

• Significant power loss or engine derate mode, especially under load during digging or lifting operations
• Check Engine Light or malfunction indicator lamp illuminated on the instrument panel
• Black or grey exhaust smoke due to improper air-fuel mixture compensation
• Poor throttle response and sluggish acceleration when increasing engine RPM
• Turbocharger lag or audible turbo performance irregularities during operation

Potential Causes

The most common technical causes for Code 108-2 in used XCMG excavators include:

• Damaged or corroded sensor connector pins – particularly common in machines exposed to water, mud, or chemical contaminants
• Wiring harness chafing or breakage at known rub points near the turbocharger mounting area where heat and vibration cause insulation failure
• Failed boost pressure sensor – internal component degradation in high-hour machines
• ECM wiring issues including poor ground connections or damaged circuits between the sensor and control module
• Sensor contamination from oil mist or carbon buildup affecting sensor diaphragm operation

How to Troubleshoot and Fix Code 108-2

Step 1: Visual Inspection Begin by inspecting the boost pressure sensor (typically mounted on the intake manifold) and its wiring harness. On used excavators, check for connector corrosion, damaged pins, oil contamination, or harness wear at mounting brackets where vibration causes friction.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and check the supply voltage at the harness connector (should read approximately 5V with key on, engine off). Test the signal wire for continuity back to the ECM and verify the ground circuit has less than 0.2 ohms resistance.

Step 3: Sensor Testing Measure the sensor's output voltage at idle and compare against manufacturer specifications. If readings are consistently below 0.5V or erratic, replace the boost pressure sensor. Before installing new parts on used machines, clean all connector contacts with electrical contact cleaner and apply dielectric grease to prevent future corrosion.

Step 4: Verification Clear the code using XCMG diagnostic software or a compatible OBD scanner, operate the machine under load, and verify the code does not return.

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Disclaimer: This guide provides general troubleshooting information. Always consult XCMG service manuals and qualified diesel technicians for repairs, especially when dealing with emission-controlled systems.