Hyundai HX220 NL EPFC Fault Code 3568 (5394-7): Meaning and Fix

What is Hyundai HX220 NL EPFC Fault Code 3568 (5394-7)?

Fault Code 3568 (5394-7) indicates a malfunction in the engine control system's communication circuit, specifically related to CAN bus data transmission errors between the Engine Control Module (ECM) and other control units. This code typically signals that the ECM is detecting intermittent or complete loss of communication on the Controller Area Network (CAN) line, which is critical for coordinating engine performance, hydraulic functions, and operator display information.

In the HX220 NL EPFC excavator, this fault directly impacts the machine's ability to synchronize engine output with hydraulic demand. When communication breaks down, the system may enter a derate mode or fail to respond properly to joystick inputs, compromising both productivity and safety on the jobsite.

Common Symptoms

• Warning light illuminated on the instrument cluster, often accompanied by a "Check Engine" or communication error message
• Reduced engine power or sudden derate, limiting maximum RPM and hydraulic flow
• Erratic hydraulic response – boom, arm, or swing functions may lag or operate inconsistently
• Intermittent gauge failures – fuel level, temperature, or pressure readings may freeze or display incorrect values
• Engine may start normally but exhibit performance issues under load or after warm-up

Potential Causes

• Damaged or corroded CAN bus wiring harness – common wear points include routing near the turbocharger, along the boom base, and through bulkhead connectors
• Loose or corroded connector pins at the ECM, instrument cluster, or hydraulic control module
• Failed termination resistor on the CAN network (typically 120-ohm resistors at network endpoints)
• ECM internal fault or software corruption requiring reprogramming
• Aftermarket accessories improperly spliced into the CAN network, creating signal interference
• Water intrusion into harness connectors, especially on used machines with compromised seals

How to Troubleshoot and Fix Code 3568 (5394-7)

Step 1: Visual Inspection
Inspect the entire CAN bus harness from the ECM to all connected modules. On used excavators, pay special attention to harness routing near heat sources (exhaust manifold, turbo) and high-flex areas (cab pivot points). Look for chafed insulation, melted wire jackets, or green corrosion on connector pins.

Step 2: Connector and Termination Check
Disconnect the ECM connector and inspect for bent pins, moisture, or corrosion. Use a multimeter to measure resistance between the CAN-High and CAN-Low terminals with all modules connected – you should read approximately 60 ohms (two 120-ohm termination resistors in parallel). A reading significantly higher suggests an open circuit or missing terminator.

Step 3: Signal Integrity Test
Using Hyundai Hi-MATE diagnostic software or an equivalent CAN bus analyzer, monitor live data traffic while operating the machine. Intermittent dropouts or error frames indicate a wiring issue. If the software shows consistent communication but the code persists, suspect an ECM internal fault.

Step 4: Repair or Replace
For harness damage, repair using OEM-spec shielded twisted-pair wire and heat-shrink solder connections – avoid crimp splices in CAN circuits. Replace corroded connectors entirely rather than cleaning. If diagnostics point to the ECM, verify software version is current before replacing the module, as reflashing may resolve the issue.

For used excavators: Always check for previous repair attempts, including aftermarket splices or non-OEM harness sections that may not meet signal integrity requirements.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hyundai service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs to CAN bus systems can cause additional faults or safety hazards.