What is Doosan Excavator Fault Code E000628-02?

Fault Code E000628-02 indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a data link error or CAN bus communication failure between the ECM and the main machine controller. This code triggers when the engine's electronic control unit cannot properly transmit or receive signals through the Controller Area Network (CAN), which is the digital nervous system connecting all electronic components in modern Doosan excavators.

This fault is critical because the CAN bus serves as the primary communication pathway between the engine management system, hydraulic controllers, and the operator display. When communication breaks down, the excavator's integrated systems cannot coordinate properly, leading to performance limitations or complete operational shutdown. In Doosan equipment, this particular code variant (-02) typically indicates an intermittent or complete loss of signal rather than incorrect data transmission, making it essential to address immediately to prevent costly downtime.

Common Symptoms

• Warning light activation on the instrument cluster, often accompanied by a "Check Engine" or communication error message on the display panel
• Engine derate mode where the machine limits power output to 50-70% capacity as a protective measure
• Intermittent loss of instrument readings, including engine RPM, temperature gauges, or hydraulic pressure displays going blank
• Erratic throttle response or sudden engine speed fluctuations without operator input
• Inability to start the machine in severe cases, or immediate shutdown after starting

Potential Causes

The most common technical reasons for E000628-02 in used Doosan excavators include:

• Corroded or damaged CAN bus connectors, particularly at the ECM harness connection points where moisture intrusion is common
• Wiring harness chafing at known rub points near the engine mount or along the right-hand chassis rail where cables contact metal edges
• Failed termination resistors at either end of the CAN network (typically 120-ohm resistors that maintain signal integrity)
• ECM internal failure or corrupted software, more common in machines with 8,000+ operating hours
• Voltage irregularities from failing batteries, corroded grounds, or alternator issues affecting the 24V supply to communication circuits
• Aftermarket accessory installation that improperly taps into the CAN network without proper isolation

How to Troubleshoot and Fix Code E000628-02

Step 1: Visual Inspection and Connection Check Begin by thoroughly inspecting all wiring harnesses between the ECM (located near the engine) and the main controller (typically under the cab). Look specifically for abraded insulation, bent connector pins, or green corrosion on terminals. Disconnect and reconnect the ECM connector and the main CAN bus connector at the controller, applying dielectric grease to prevent future moisture issues.

Step 2: Electrical Testing with Diagnostic Tools Using a digital multimeter, measure the resistance between the CAN-High and CAN-Low wires at the ECM connector with the ignition off and all modules disconnected. You should read approximately 60 ohms (two 120-ohm termination resistors in parallel). A reading of 120 ohms indicates one missing terminator; infinite resistance means an open circuit in the network. Check for voltage presence on the CAN lines with ignition on—there should be approximately 2.5V DC on each line at rest.

Step 3: Advanced Diagnostics and Component Testing Connect Doosan diagnostic software (DMS-5 or equivalent) to retrieve detailed failure data and monitor real-time CAN bus activity. Perform a "wiggle test" by gently flexing harnesses while monitoring for communication dropouts. For used excavators, pay particular attention to harness routing near hydraulic lines where heat and vibration accelerate insulation breakdown. If all wiring tests pass, the ECM itself may require reflashing or replacement—verify with Doosan technical support before replacing this expensive component.

Step 4: Verify Repair and Clear Code After addressing identified issues, clear the fault code using diagnostic software and operate the machine through a complete work cycle. Monitor for code recurrence over several hours, as intermittent communication faults may not appear immediately.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Doosan service manual for your specific model and serial number. If you lack proper diagnostic equipment or electrical system experience, contact a certified Doosan service technician to prevent further damage to electronic components.