What is Komatsu PC110-8M0 Fault Code E-24?

Fault Code E-24 on the Komatsu PC110-8M0 indicates a malfunction in the Engine Controller (ECM) communication circuit or a failure in the controller's internal voltage supply system. This diagnostic trouble code specifically points to an electrical irregularity between the Engine Control Module (ECM) and the machine's main monitoring system, preventing proper data exchange about engine operating parameters.

The E-24 code is critical for the PC110-8M0 because this mid-sized excavator relies heavily on integrated electronic controls to regulate engine performance, fuel injection timing, and emissions control. When communication fails, the ECM cannot properly adjust fuel delivery or monitor critical sensors, potentially leading to reduced power output, increased fuel consumption, or engine protection mode activation. In used excavators, this code often appears due to age-related electrical degradation rather than catastrophic component failure.

Common Symptoms

When Code E-24 is active on your Komatsu PC110-8M0, operators typically experience:

• Engine warning light illuminated continuously on the instrument panel
• Sudden engine power reduction or entry into derate mode (limiting RPM to 1,200-1,500)
• Intermittent loss of throttle response, particularly during hydraulic work under load
• Erratic instrument cluster readings, including inaccurate fuel level or temperature displays
• Hard starting or extended cranking before engine fires, especially in cold conditions

Potential Causes

The E-24 fault code on used PC110-8M0 excavators typically stems from these technical issues:

• Corroded or loose ECM connectors (particularly the 48-pin main harness connector located near the fuel filter assembly)
• Failed ECM internal power supply circuit due to voltage spikes or age-related capacitor deterioration
• Damaged wiring harness between ECM and instrument cluster, often rubbing against the frame near the right-side cab mount
• Low battery voltage or failing alternator creating insufficient power supply (below 22V on this 24V system)
• Water intrusion into the ECM housing, common on machines operating in wet or humid environments
• Aftermarket electrical accessories incorrectly wired into the main power distribution, causing voltage irregularities

How to Troubleshoot and Fix Code E-24

Step 1: Perform Visual and Electrical Inspections

Begin by checking battery voltage with a multimeter—it should read 24-26V with the engine off. Inspect all ground connections at the ECM mounting bracket and battery negative terminals for corrosion. On used excavators, remove the ECM's 48-pin connector and examine pins for bent terminals, green corrosion, or moisture. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Test ECM Power Supply Circuit

Using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, monitor live ECM voltage while cranking. The ECM should receive constant 24V power. Check the 30A fuse in the main fuse box (position F-7) dedicated to ECM power. Trace the red/white power wire from the fuse box to the ECM for any chafing points—particularly where the harness crosses the engine valley near the turbocharger heat shield.

Step 3: Verify Communication Network Integrity

Inspect the CAN bus communication lines (twisted yellow/green pair) between the ECM and instrument cluster. Measure resistance between CAN-High and CAN-Low terminals at the ECM connector—it should read 55-65 ohms. For used machines, check for harness wear at the cab pivot point, a known weak spot on PC110-8 models with over 5,000 operating hours.

Step 4: ECM Replacement Decision

If all wiring tests pass and voltage supply is correct, the ECM itself may have internal failure. Before replacing this $1,200-1,800 component on a used excavator, verify the part number (typically 7835-46-1004 for PC110-8M0) and consider having your existing ECM tested by a Komatsu-authorized rebuilder. Always clear codes and perform a cold restart test after repairs to confirm the fix.

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Disclaimer: This guide provides general diagnostic information for experienced technicians. Always consult the official Komatsu PC110-8M0 service manual and consider professional evaluation, especially for used machines with unknown maintenance history. Improper electrical diagnostics can cause additional damage to sensitive electronic components.