What is Komatsu PC210LC-7 Fault Code E112?

Fault Code E112 on the Komatsu PC210LC-7 indicates a malfunction in the Engine Control Module (ECM) communication system, specifically a CAN Bus communication error between the engine controller and the machine's monitoring system. This code triggers when the ECM fails to send or receive proper data signals through the Controller Area Network (CAN) datalink, disrupting the communication between critical control units.

This fault is particularly critical for the PC210LC-7 because the SAA6D107E-1 engine relies on continuous ECM communication to manage fuel injection timing, turbocharger control, and emission systems. When communication breaks down, the machine cannot properly monitor engine parameters, potentially leading to performance degradation, excessive fuel consumption, or unexpected shutdowns. For used excavators, this code often stems from connector corrosion or wiring harness deterioration rather than ECM failure itself.

Common Symptoms

• Warning light illumination on the instrument panel, specifically the engine diagnostic lamp remaining solid or flashing
• Loss of engine power or activation of derate mode, limiting machine to reduced RPM and hydraulic performance
• Intermittent gauge failures, including erratic fuel level, coolant temperature, or engine hour readings on the monitor
• Inability to access diagnostic information through the monitor panel, with blank or frozen display screens
• Hard starting conditions or unexpected engine stalling during operation, particularly when the machine is hot

Potential Causes

The most common technical causes for E112 on used PC210LC-7 excavators include:

• CAN Bus wiring harness damage at known friction points near the engine mount and along the right-hand chassis rail where cables rub against frame members
• Corroded or loose connectors at the ECM (located behind the operator cab) or at the main machine controller junction box
• Faulty termination resistors within the CAN network, typically found at network endpoints
• ECM internal failure due to moisture intrusion, though this is less common than wiring issues in older machines
• Low system voltage from weak batteries or failing alternators, causing communication protocol errors
• Aftermarket component interference, particularly non-OEM monitors or telematics devices improperly installed on the CAN network

How to Troubleshoot and Fix Code E112

Step 1: Visual Inspection of Harnesses and Connectors Begin by thoroughly inspecting the main wiring harness between the ECM and the machine controller. On used excavators, focus on areas where harnesses pass through bulkheads or contact metal edges. Disconnect the 25-pin ECM connector and the CAN Bus connector at the junction box (located under the right-hand console). Check for green corrosion, bent pins, or moisture inside connector bodies. Clean all connections with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: Test CAN Bus Continuity and Resistance Using a digital multimeter, measure the resistance between CAN-High and CAN-Low terminals at the ECM connector (terminals typically labeled as CANH and CANL in the service manual). You should read approximately 60 ohms with the key off and all controllers connected, indicating proper termination resistors. Readings above 100 ohms or below 40 ohms suggest open circuits or shorted termination resistors. Also check for continuity between each CAN wire and ground—there should be no continuity (infinite resistance).

Step 3: Verify Power Supply and Ground Circuits Check the ECM power supply voltage at the connector using your multimeter with the key on. You should measure battery voltage (12-14V) at the power pins. Inspect the ECM ground connections at the engine block mounting point for tightness, corrosion, or paint buildup that prevents solid grounding. Poor grounds are a frequent culprit in used machinery.

Step 4: Use Komatsu KOMTRAX or Diagnostic Software Connect Komatsu diagnostic software (KTEC) or a compatible scan tool to retrieve detailed ECM data and perform active communication tests. The software can identify which specific controller is failing to communicate and log intermittent faults that may not trigger the code continuously. This is essential for used excavators with multiple previous repairs.

Step 5: Isolate Aftermarket Devices If aftermarket telematics, GPS trackers, or non-OEM monitors have been installed, temporarily disconnect them from the CAN network and clear the code. Improperly installed devices can create network conflicts or voltage drops that trigger E112. Reconnect devices one at a time to identify the culprit.

Step 6: Replace Components as Necessary If diagnostics confirm ECM failure after ruling out wiring issues, replacement of the Engine Control Module is required. Ensure the replacement ECM is programmed with the correct software version for the PC210LC-7 using Komatsu diagnostic tools. Before replacing the ECM, consider testing with a known-good unit if available, as ECM failures are relatively rare compared to wiring problems.

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Disclaimer: This guide provides general diagnostic procedures for experienced technicians. Always consult the official Komatsu PC210LC-7 service manual and consider professional diagnosis if unfamiliar with electrical systems. Improper repairs can cause additional damage or safety hazards.