What is XCMG XE490D Fault Code 1667?

Fault Code 1667 indicates a high voltage condition detected in the Engine Speed/Position Sensor Circuit (Cummins CM2250 engine). This diagnostic trouble code (DTC) triggers when the Engine Control Module (ECM) detects an abnormal voltage signal—typically above 4.5 volts—from the crankshaft or camshaft position sensor circuit, exceeding the manufacturer's specified range.

This fault is critical for the XCMG XE490D equipped with the Cummins CM2250 diesel engine because these position sensors provide essential timing data for fuel injection, ignition events, and overall engine synchronization. Without accurate sensor readings, the ECM cannot properly control engine performance, potentially leading to reduced power output or complete engine shutdown to prevent damage.

Common Symptoms

When Fault Code 1667 is active on your XCMG excavator, operators typically experience:

• Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated on the dashboard
• Engine derate mode limiting maximum RPM and hydraulic performance
• Hard starting conditions or extended cranking time before the engine fires
• Rough idle or engine stumbling during operation, particularly under load
• Intermittent engine stalling or unexpected shutdowns during digging cycles

Potential Causes

The most common technical causes for Code 1667 on used XCMG excavators include:

• Damaged or frayed sensor wiring harness, especially at known rub points near the engine block or transmission bell housing
• Corroded or moisture-contaminated connectors at the crankshaft/camshaft position sensor
• Failed crankshaft position sensor due to excessive heat exposure or internal component breakdown
• ECM internal circuit fault causing improper voltage supply to the sensor circuit
• Intermittent short-to-power condition where sensor wiring contacts battery voltage due to harness routing issues
• Aftermarket sensor incompatibility if non-OEM parts were previously installed during repairs

How to Troubleshoot and Fix Code 1667

Step 1: Visual Inspection Perform a thorough inspection of the engine speed/position sensor harness from the ECM connection to the sensor itself. On used excavators, check for wire insulation damage, particularly where the harness passes near hot exhaust components or moving engine parts. Inspect all connector pins for corrosion, bent terminals, or moisture intrusion.

Step 2: Voltage Testing Using a digital multimeter (DVOM), measure the voltage at the sensor connector with the key on, engine off. The reference voltage should read approximately 5 volts (±0.5V). If voltage exceeds 4.8 volts at the sensor or shows fluctuation, suspect wiring issues or ECM problems. Check for short-to-power conditions by measuring resistance between the signal wire and battery positive with all connections disconnected.

Step 3: Sensor Resistance Check Disconnect the crankshaft position sensor and measure resistance across its terminals. Cummins CM2250 sensors typically show 150-300 ohms at room temperature. Values outside this range indicate sensor failure requiring replacement with genuine Cummins parts.

Step 4: Harness Continuity and Ground Testing Verify complete circuit continuity from the ECM connector to the sensor connector, and check for proper grounding. Resistance should be less than 5 ohms for signal wires and less than 2 ohms for ground circuits.

Step 5: Advanced Diagnostics Connect Cummins INSITE or compatible diagnostic software to monitor live sensor data and voltage patterns during cranking. This identifies intermittent faults common in aging equipment.

For used excavators, always replace connector seals and protective boots during sensor replacement to prevent future moisture-related failures.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official XCMG service manual and consider professional diagnostic services for complex electrical issues. Improper repairs may void warranties or cause additional damage.