What is XCMG XE750D Fault Code 2535-6 SPN1073 FMI6?

Fault Code 2535-6 (SPN1073 FMI6) indicates a problem with the Engine Intercooler Temperature Sensor Circuit, specifically a voltage signal that is above the normal operating range or experiencing a short to high voltage source. This diagnostic trouble code is part of the J1939 standard used in modern diesel engine management systems.

On the XCMG XE750D excavator, SPN 1073 refers specifically to the Charge Air Cooler (Intercooler) Temperature Sensor, while FMI 6 indicates "data above normal or shorted to high source." The Engine Control Module (ECM) monitors this sensor to optimize fuel injection timing, air-fuel ratios, and turbocharger performance. When intake air temperature readings are unreliable, the engine may enter a protective derate mode to prevent damage from poor combustion or overheating.

This fault is critical because the intercooler temperature directly affects combustion efficiency. Inaccurate readings can lead to reduced power output, increased fuel consumption, and potential long-term engine damage on high-hour used machines.

Common Symptoms

When fault code 2535-6 is active on your XE750D, you may experience:

• Check Engine Light or MIL (Malfunction Indicator Lamp) illuminated on the dashboard
• Engine power derate or noticeable loss of hydraulic performance during heavy digging operations
• Rough idle or hesitation during throttle response
• Black smoke from the exhaust due to incorrect air-fuel mixture calculations
• Engine may default to a substitute temperature value, causing poor cold-start performance

Potential Causes

The most common technical reasons for this fault code on used XCMG excavators include:

• Damaged or corroded wiring harness near the intercooler area, especially where harnesses contact frame rails or pass through bulkheads (common wear point on XE750D models)
• Failed intercooler temperature sensor due to heat cycling and age-related deterioration
• Shorted sensor signal wire to battery voltage (+12V or +24V depending on system)
• Corroded or moisture-contaminated connector pins at the sensor or ECM connection points
• ECM internal fault (less common but possible on high-hour used machines)
• Aftermarket repairs or modified wiring causing improper voltage reference

How to Troubleshoot and Fix Code 2535-6 SPN1073 FMI6

Step 1: Visual Inspection Begin with a thorough physical inspection of the intercooler temperature sensor and its wiring harness. On used excavators, focus on areas where the harness routes near sharp edges, hot surfaces, or moving components. Look for chafed insulation, melted wires, or corrosion on the sensor connector. Disconnect the sensor and inspect the pins for green corrosion or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and check the signal wire voltage with the ignition on. You should see approximately 5 volts (reference voltage from the ECM). If you measure battery voltage (12V/24V), there's a short to power in the harness. Next, measure the sensor resistance according to XCMG specifications (typically 2,000-3,000 ohms at room temperature, decreasing as temperature rises). Compare your readings to the manufacturer's resistance-temperature chart.

Step 3: Advanced Diagnostics Connect XCMG diagnostic software or a compatible J1939 scan tool to monitor live sensor data. Compare the intercooler temperature reading to ambient temperature at cold start—they should be nearly identical. If the sensor reads correctly when cold but faults under operation, suspect intermittent wiring issues caused by vibration or heat expansion. Check for harness rub points specific to the XE750D near the turbocharger outlet and along the right-side frame rail.

Step 4: Repair and Verification If wiring is damaged, repair using high-temperature automotive wire and heat-shrink connectors—avoid electrical tape in engine compartments. Replace the sensor if resistance values are out of specification. For used machines, consider applying dielectric grease to all connectors to prevent future corrosion. After repairs, clear codes with diagnostic software and perform a test cycle under load to verify the fix.

---

Disclaimer: This guide provides general troubleshooting information for educational purposes. Always consult the official XCMG service manual for your specific machine serial number and torque specifications. If you're unfamiliar with electrical diagnostics or working on high-voltage systems, seek assistance from a certified heavy equipment technician to avoid injury or further damage to the machine.