Komatsu PC210LC-8 Fault Code E11 CA155: Meaning, Symptoms, and Fix

What is Komatsu PC210LC-8 Fault Code E11 CA155?

Fault Code E11 CA155 indicates a communication error between the Engine Controller (ECM) and the Pump Controller (PMC) on the Komatsu PC210LC-8 excavator. This diagnostic trouble code specifically signals that the CAN (Controller Area Network) bus communication link has failed or is experiencing intermittent signal degradation between these two critical controllers.

The ECM manages engine performance parameters while the PMC regulates hydraulic pump output. When these controllers cannot communicate properly, the machine's integrated control system cannot optimize fuel efficiency and hydraulic performance simultaneously. This is particularly critical on the PC210LC-8, which relies on coordinated ECM-PMC communication for its advanced CLSS (Closed-Center Load Sensing System) to function correctly. Without proper communication, the excavator may enter a protective derate mode to prevent component damage.

Common Symptoms

When Code E11 CA155 is active, operators typically experience:

• Yellow warning light illuminated on the monitor panel with fault code display
• Reduced hydraulic response or sluggish boom/arm movements due to pump output limitation
• Engine power derate limiting RPM to approximately 1,500-1,800 range
• Intermittent loss of hydraulic power that may come and go during operation
• Monitor display errors showing communication failure messages between systems

Potential Causes

The most common technical reasons for E11 CA155 on used PC210LC-8 excavators include:

• CAN bus harness damage between ECM and PMC, particularly at known rub points near the hydraulic pump mounting area
• Corroded or loose connector pins at the ECM (located behind cab) or PMC (mounted on main pump)
• Failed termination resistor within the CAN network circuit (120-ohm resistance required)
• Water intrusion into controller connectors causing internal circuit board corrosion
• Voltage supply issues to either controller due to failing main relay or damaged power supply wiring
• ECM or PMC internal failure, though less common than wiring/connector issues in used machines

How to Troubleshoot and Fix Code E11 CA155

Step 1: Visual Inspection Begin with a thorough physical examination of the CAN bus harness routing from the ECM to the PMC. On used excavators, check for harness abrasion against the hydraulic pump housing, particularly where the wiring passes through the engine compartment firewall. Inspect all connector terminals for corrosion, bent pins, or moisture intrusion. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Electrical Testing Using a digital multimeter, verify CAN bus communication lines. Disconnect both ECM and PMC connectors. Measure resistance between CAN-High and CAN-Low terminals—you should read approximately 60 ohms with both controllers disconnected (indicating proper 120-ohm termination resistors in parallel). Check for short circuits to ground on both CAN lines (should read infinite resistance). Verify power supply voltage at PMC connector (should be 24V with key on).

Step 3: Controller Communication Test Reconnect all connectors and use Komatsu KOMTRAX diagnostic software or compatible scan tool to monitor live CAN bus data. Observe communication frame rates between controllers. If communication is intermittent, perform a wiggle test on harnesses while monitoring—this often reveals fractured wires inside insulation. For used excavators with high hours (>8,000), replace the entire ECM-to-PMC harness as preventive maintenance, as internal wire fatigue is common.

Step 4: Component Replacement If wiring and connections test properly, substitute-test controllers if available. Replace the PMC first as it's more commonly affected by hydraulic system heat and vibration. If fault persists, the ECM may require replacement or professional reprogramming.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional system damage.