What is XCMG XE750D Fault Code 2302-3 SPN109 FMI3?

Fault Code 2302-3 (SPN109 FMI3) indicates a voltage issue with the Turbocharger Inlet Pressure (Boost Pressure) sensor circuit, specifically showing a voltage above normal or shorted to a higher voltage source. This is a critical diagnostic code on the XCMG XE750D excavator's engine control system.

SPN109 refers to the Turbocharger Inlet Pressure sensor, while FMI3 designates the fault type as "voltage above normal or shorted high." The Engine Control Module (ECM) continuously monitors boost pressure to optimize fuel injection, protect against over-boost conditions, and maintain emissions compliance. On large excavators like the XE750D, improper boost pressure readings can trigger engine derates or prevent the machine from developing full power, directly impacting productivity on job sites.

Common Symptoms

• Check Engine Light or Malfunction Indicator Lamp (MIL) illuminated on the instrument cluster
• Engine power derate or reduced hydraulic performance, especially under heavy loads
• Black smoke from exhaust due to improper air-fuel ratio calculations
• Poor throttle response or hesitation during acceleration
• ECM logging multiple instances of the fault, potentially triggering limp mode on newer software versions

Potential Causes

The most common technical causes for Code 2302-3 on used XCMG excavators include:

• Damaged or chafed wiring harness near the turbocharger, where high heat and vibration cause insulation breakdown and shorting to chassis ground or 12V+ circuits
• Corroded or moisture-infiltrated connectors at the boost pressure sensor, common in machines operating in wet or humid environments
• Failed boost pressure sensor with internal circuit degradation (typical after 5,000+ operating hours)
• Shorted sensor supply voltage from the ECM due to pinched wires in harness routing near engine mounts
• ECM internal fault (less common) affecting the 5V sensor reference circuit

How to Troubleshoot and Fix Code 2302-3 SPN109 FMI3

Step 1: Visual Inspection Locate the turbocharger inlet pressure sensor (typically mounted on the intake manifold or intercooler piping). Inspect the wiring harness for obvious damage, melting, or wear points where wires contact hot surfaces or sharp edges. On used excavators, check for oil contamination on connectors, which can cause voltage leakage.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across sensor terminals (typically 150-250 ohms at room temperature—consult XCMG service manual for exact specs). Check supply voltage from the ECM: you should see approximately 5V DC on the reference wire with ignition on, engine off.

Step 3: Harness Continuity Check Test for shorts to power by measuring voltage between each sensor wire and chassis ground with the sensor disconnected. Any reading above 0.5V indicates a short. Inspect harness routing and repair/replace damaged sections with heat-resistant loom and proper grommets.

Step 4: Component Replacement If the sensor tests faulty, replace with a genuine XCMG or OEM-equivalent boost pressure sensor. After replacement, clear codes using diagnostic software and perform a road test under load to verify repair.

Disclaimer: This guide provides general troubleshooting steps. Always consult the official XCMG service manual for your specific machine serial number and software version. Complex electrical diagnostics should be performed by qualified diesel technicians with proper diagnostic tools.