What is XCMG XE490D (CM2250) Fault Code 1968?

Fault Code 1968 indicates a Fuel Injector Solenoid Circuit - Cylinder 6 - High Side Short to Ground. This Cummins CM2250 engine-specific code means the Engine Control Module (ECM) has detected an electrical short circuit on the high-side driver circuit for the number 6 cylinder fuel injector. The injector solenoid is receiving an abnormal ground path, preventing proper fuel delivery control to that cylinder.

This fault is critical for the XCMG XE490D because it directly affects combustion efficiency, causing power loss and potentially damaging the catalytic aftertreatment system through unburned fuel. The CM2250 engine relies on precise electronic fuel injection timing, and a cylinder-specific short can create imbalanced loads on the hydraulic system during digging or lifting operations.

Common Symptoms

• Engine derate mode activated with noticeable power reduction (typically 25-40% torque limitation)
• Check Engine Light (CEL) or amber warning lamp illuminated on the instrument cluster
• Rough idling or misfiring sensation, particularly noticeable at low RPMs or during warm-up
• Black or gray exhaust smoke due to incomplete combustion in cylinder 6
• Increased fuel consumption and difficulty maintaining consistent hydraulic flow under load

Potential Causes

The most common causes for Code 1968 on used XCMG excavators with CM2250 engines include:

• Damaged injector wiring harness where the cylinder 6 injector lead runs along the valve cover (common rub point from engine vibration)
• Failed fuel injector solenoid with internal short to ground condition
• Corroded or moisture-contaminated injector connector pins (especially on machines operating in wet or marine environments)
• Chafed wiring near the engine harness mounting brackets between the ECM and injector
• Faulty ECM high-side driver circuit (less common but possible in high-hour machines)

How to Troubleshoot and Fix Code 1968

Step 1: Visual Inspection Perform a thorough inspection of the cylinder 6 injector harness from the ECM connector to the injector itself. On used excavators, check for wire insulation damage at known rub points near the rocker cover and fuel rail. Inspect the injector connector for corrosion, bent pins, or moisture intrusion.

Step 2: Electrical Testing Disconnect the cylinder 6 injector connector. Using a digital multimeter (DMM), measure resistance from the injector high-side terminal to engine ground. You should read open circuit (OL or infinite resistance). If you measure less than 10k ohms, the injector has an internal short and requires replacement. Check harness-side resistance to ground with the ECM connector disconnected—it should also read open circuit.

Step 3: Injector and Harness Verification If wiring tests pass, swap the cylinder 6 injector with another cylinder (like cylinder 5) and clear codes. If Code 1968 moves to the new cylinder location, replace the injector solenoid assembly. If the code stays at cylinder 6, replace the engine harness section for that injector circuit. Use Cummins Insite or XCMG diagnostic software to perform injector cutout tests to verify proper operation after repairs.

For used machines, always apply dielectric grease to connectors during reassembly to prevent future corrosion-related faults.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official XCMG and Cummins service manuals for your specific machine serial number. Complex electrical diagnostics should be performed by certified technicians with proper diagnostic equipment.