What is XCMG XE750D Fault Code 3096-6 SPN4337 FMI6?

Fault Code 3096-6 (SPN 4337 FMI 6) indicates a voltage issue with the Diesel Exhaust Fluid (DEF) Pump Motor Circuit, specifically a "current below normal or open circuit" condition. This code is triggered when the Engine Control Module (ECM) detects insufficient electrical current flowing through the DEF pump motor circuit, suggesting an open circuit, poor connection, or failed pump motor.

On the XCMG XE750D excavator, this fault directly impacts the Selective Catalytic Reduction (SCR) aftertreatment system. The DEF pump is responsible for injecting diesel exhaust fluid into the exhaust stream to reduce NOx emissions. When this circuit fails, the machine may enter derate mode or prevent startup to comply with emissions regulations, severely affecting jobsite productivity.

Common Symptoms

• Amber or red DEF warning light illuminated on the instrument cluster
• Engine power derate (reduced horsepower and torque output) after a grace period
• DEF system malfunction message displayed on the monitor screen
• Inability to start the engine after extended periods with the fault active (emission-related lockout)
• Audible warning alarms indicating SCR system failure

Potential Causes

The most common technical causes for this fault code on used XCMG XE750D excavators include:

• Failed DEF pump motor due to internal winding breakdown or seized rotor (common in machines with 5,000+ hours)
• Corroded or damaged wiring harness connections at the DEF pump connector, especially where harness routing causes vibration wear
• Open circuit in the pump motor wiring, often found at flex points near the DEF tank mounting bracket
• Faulty ECM relay or fuse supplying power to the DEF pump circuit
• ECM internal driver circuit failure (less common but possible in older machines)
• Damaged pins or moisture intrusion in the DEF pump electrical connector

How to Troubleshoot and Fix Code 3096-6 SPN4337 FMI6

Step 1: Visual Inspection Begin by inspecting the DEF pump wiring harness from the pump connector to the ECM. On used excavators, check for chafed wires, corroded terminals, or damaged insulation at known rub points near the fuel tank and chassis mounting brackets. Remove the connector at the DEF pump and inspect for bent pins, corrosion, or moisture.

Step 2: Electrical Testing Using a digital multimeter (DMM), perform a continuity test on the pump motor circuit wiring. With the ignition off and connector disconnected, check for open circuits between the pump connector and ECM connector pins (refer to XCMG wiring diagrams). Check resistance across the DEF pump motor terminals—typical readings should be 2-8 ohms. Infinite resistance indicates a failed motor.

Step 3: Power Supply Verification With ignition on, measure voltage at the DEF pump connector using the multimeter. You should see battery voltage (12-14V) when the ECM commands the pump on. If voltage is absent, trace back to check the relay, fuse, and ECM outputs. Replace faulty relays or repair open circuits as needed.

Step 4: Component Replacement If wiring and power supply are intact but resistance testing confirms pump motor failure, replace the DEF pump assembly. For used machines, always replace the pump connector pigtail simultaneously to prevent future corrosion issues. Clear the fault code using XCMG diagnostic software and perform a DEF system prime procedure.

Disclaimer: This guide provides general troubleshooting information. Always consult the XCMG XE750D service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs to emissions systems may violate environmental regulations.