What is Sany SY245/265H Fault Code 98?

Fault Code 98 on the Sany SY245/265H excavator indicates a communication error between the engine ECM (Engine Control Module) and the machine's main controller or display unit. This code is specific to the Mitsubishi Heavy Industries diesel engine used in these models and signals a breakdown in the CAN (Controller Area Network) bus communication protocol.

The CAN bus system is critical for the SY245/265H's operation because it allows the engine ECM to communicate vital performance data—such as engine speed, temperature, fuel delivery, and diagnostic information—to the operator's display and main machine controller. When this communication fails, the machine cannot properly monitor engine parameters or execute coordinated hydraulic and engine functions, potentially leading to reduced productivity and undiagnosed engine issues.

Common Symptoms

• Warning lights illuminated on the dashboard, including the engine malfunction light or communication error indicator
• Intermittent or complete loss of engine data on the operator display (RPM, coolant temperature, fuel level showing incorrectly or not at all)
• Engine derate mode activation, limiting machine power output as a protective measure
• Erratic hydraulic performance due to improper communication between engine load and hydraulic demand
• Inability to access diagnostic codes or real-time engine data through the machine's display

Potential Causes

The most common technical causes for Code 98 on used SY245/265H excavators include:

• Damaged or corroded CAN bus wiring harness, particularly at known rub points near the engine mounting brackets and along the boom base where vibration and movement cause wear
• Loose or corroded connectors at the ECM or main controller, especially on machines operating in wet or corrosive environments
• Failed termination resistors on the CAN bus network (typically 120-ohm resistors at each end of the bus)
• ECM internal fault or corrupted software/firmware within the engine control module
• Voltage irregularities from failing batteries, alternator issues, or poor grounding affecting CAN bus signal integrity
• Water intrusion into connector housings, common on older excavators with deteriorated seals

How to Troubleshoot and Fix Code 98

Step 1: Visual Inspection of Wiring and Connectors Begin by thoroughly inspecting the CAN bus harness running between the engine ECM (located on the engine block) and the main controller. On used excavators, pay special attention to areas where the harness passes through metal grommets or rubs against the frame. Look for frayed wires, damaged insulation, or signs of harness abrasion. Check all connector pins for corrosion, bent terminals, or moisture intrusion.

Step 2: Test CAN Bus Continuity and Resistance Using a digital multimeter, disconnect both ends of the CAN bus and measure resistance between the CAN-High and CAN-Low wires. You should read approximately 60 ohms when both termination resistors are functional (two 120-ohm resistors in parallel). If you measure infinite resistance, one or both termination resistors have failed. Check each resistor individually by accessing the ECM and main controller connectors.

Step 3: Verify Power Supply and Grounding Check that the ECM is receiving proper voltage (typically 24V on these machines). Measure voltage at the ECM connector with the key on. Also verify ground integrity by measuring resistance between the ECM ground terminal and a known good chassis ground—it should read less than 1 ohm. Poor grounding is a frequent issue on used machines with corroded ground straps.

Step 4: Check for Software and ECM Issues Connect Mitsubishi diagnostic software or compatible scan tool to read detailed communication logs. If physical wiring checks pass but communication remains unstable, the ECM may require firmware updates or replacement. Before replacing the ECM on a used excavator, ensure all harness repairs are complete, as premature ECM replacement is costly and often unnecessary.

Step 5: Clear Code and Monitor After repairs, clear the fault code and operate the machine under normal working conditions while monitoring for code recurrence. Intermittent codes often indicate harness flex points that need additional securing or rerouting.

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Disclaimer: This guide provides general troubleshooting information for Sany SY245/265H Fault Code 98. Always consult the manufacturer's service manual and consider professional diagnostic assistance for complex electrical issues, especially on used equipment with unknown service history.