What is Sany General Fault Code P995?

Fault Code P995 on Sany excavators indicates a communication error or malfunction in the machine's CAN (Controller Area Network) bus system, specifically related to data transmission failures between the main controller and peripheral control modules. This diagnostic trouble code (DTC) signals that the Electronic Control Module (ECM) has detected inconsistent or interrupted communication signals on the network, preventing proper coordination between critical systems like the engine controller, hydraulic controller, and display monitor.

This fault is particularly critical for Sany excavators because the CAN bus serves as the central nervous system for the machine, enabling real-time data exchange between all electronic components. When communication breaks down, the excavator may enter a protective derate mode or experience erratic system behavior, directly impacting productivity and potentially causing unsafe operating conditions on jobsites.

Common Symptoms

• Warning light illumination on the instrument cluster, often accompanied by error messages on the digital display screen
• Intermittent or complete loss of display functions, including gauge readings, backup camera, or operational parameters
• Reduced engine power or hydraulic response as the ECM enters a fail-safe mode to protect components
• Erratic behavior of electrical accessories, such as lights, wipers, or climate control cycling on and off
• Multiple simultaneous fault codes appearing together, indicating widespread communication failure across systems

Potential Causes

In used Sany excavators, fault code P995 typically stems from physical deterioration rather than component failure. Common causes include:

• Corroded or loose CAN bus connectors at junction points, especially behind the operator cab or near the engine compartment where moisture accumulates
• Damaged wiring harnesses due to chafing against metal edges, particularly along the swing bearing area or boom pivot points
• Failed termination resistors at the ends of the CAN network, which are essential for signal integrity
• Faulty ECM or display module with internal circuit board degradation from age or vibration exposure
• Low voltage conditions from aging batteries or failing alternators affecting network stability
• Aftermarket component interference from improperly installed accessories tapping into the electrical system

How to Troubleshoot and Fix Code P995

Step 1: Visual Inspection and Connector Check Begin with a thorough physical examination of all CAN bus wiring harnesses and connectors. Focus on areas prone to wear in used machines—check behind panels, along articulation points, and anywhere harnesses pass through bulkheads. Look for green corrosion, bent pins, or moisture intrusion in connector housings. Clean all connections with electrical contact cleaner and apply dielectric grease to prevent future corrosion.

Step 2: Electrical Testing Using a digital multimeter, verify proper termination resistance across the CAN High and CAN Low lines—you should measure approximately 60 ohms with the key off and all modules connected. Check for voltage consistency (typically 2.5V nominal with 1-2V fluctuation during communication). Inspect battery voltage under load; low voltage (below 12V) can cause intermittent communication failures.

Step 3: Diagnostic Software Analysis Connect Sany-approved diagnostic software or a compatible scan tool to read live data streams and pinpoint which specific module is losing communication. Monitor the CAN bus traffic while wiggling harnesses to identify intermittent connection points. For used excavators, pay special attention to harness friction points where years of vibration may have worn through insulation, causing short circuits.

Step 4: Component Replacement If diagnostics isolate a specific failed module, replace only after confirming wiring integrity. For older machines, consider replacing entire harness sections rather than attempting repairs, as hidden internal wire damage often exists. Replace termination resistors if readings are incorrect—these small components frequently fail but are often overlooked.

Disclaimer: This guide provides general troubleshooting information for educational purposes. CAN bus systems are complex and require proper diagnostic equipment. Always consult Sany service documentation and consider professional assistance from certified technicians, especially when working with critical electronic systems on used heavy equipment.