What is Komatsu PC210LC-10 Fault Code DXE4KA?

Fault Code DXE4KA on the Komatsu PC210LC-10 indicates a communication error between the Machine Control Unit (MCU) and the Engine Control Module (ECM). This diagnostic trouble code (DTC) signals that the machine's main computer cannot properly exchange data with the engine's electronic control system, disrupting the integrated monitoring and control functions essential for optimal excavator performance.

This code is critical because the PC210LC-10 relies on seamless CAN bus communication between control modules to manage engine parameters, hydraulic functions, and emission controls. When communication breaks down, the excavator may enter a protective derate mode or limit certain functions to prevent potential damage. For used excavators, this code often points to deteriorated wiring harnesses or corroded connectors—common issues in machines with 5,000+ operating hours.

Common Symptoms

• Yellow or red warning light illuminated on the instrument cluster, often accompanied by "Communication Error" message on the monitor
• Reduced engine power or sudden derate to lower RPM, limiting digging force and travel speed
• Intermittent loss of monitor display data, such as missing coolant temperature, fuel level, or system pressure readings
• Hydraulic system limitations, including restricted swing speed or attachment function lockouts
• Engine may fail to start in severe cases, or start with immediate fault code display

Potential Causes

The most common causes of DXE4KA on used PC210LC-10 excavators include:

• Damaged or corroded CAN bus wiring harness, particularly at rub points near the engine mount, swing bearing, or behind the operator cab where harnesses flex repeatedly
• Loose or oxidized connector contacts at the ECM or MCU connections, especially in machines exposed to moisture or extreme temperatures
• Failed termination resistor in the CAN network, causing signal reflection and communication instability
• ECM or MCU firmware corruption or internal module failure, more common in older excavators with original electronics
• Low voltage conditions from aging batteries or failing alternators, dropping below the 9-volt threshold needed for stable module communication

How to Troubleshoot and Fix Code DXE4KA

Step 1: Inspect Physical Connections Begin by disconnecting the battery and visually examining all connectors at the ECM (located under the right-side access panel) and MCU (behind the monitor panel). Look for green corrosion, bent pins, or moisture intrusion. Clean contacts with electrical contact cleaner and apply dielectric grease before reconnection.

Step 2: Test CAN Bus Wiring Integrity Using a digital multimeter, check continuity and resistance on the CAN-H and CAN-L wires between ECM and MCU. You should measure approximately 60 ohms resistance between these two lines with all modules connected. Inspect harness routing for chafing points along the engine bay firewall and undercarriage frame—common wear areas on used machines.

Step 3: Verify Power Supply and Ground Circuits Measure voltage at both modules with the key in the ON position. The ECM should show battery voltage (12-14V) on its main power pin. Check ground circuit resistance to chassis; readings above 0.5 ohms indicate poor grounding requiring cleaning and retightening. For used excavators, corrosion on ground straps near the battery box is particularly common.

Step 4: Use Komatsu Diagnostic Software Connect Komatsu KOMTRAX or compatible diagnostic tool to read active and stored fault data. Monitor live CAN bus traffic to identify intermittent dropouts. Clear codes after repairs and perform an operational test cycle including swing, boom, and travel functions under load.

Disclaimer: This guide provides general troubleshooting information. Complex electrical issues may require professional diagnosis with manufacturer-specific equipment. Always consult the PC210LC-10 service manual and consider certified Komatsu technician assistance for persistent communication faults.