What is Komatsu PC210-10 Fault Code E-37?

Fault Code E-37 on the Komatsu PC210-10 excavator indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically related to CAN (Controller Area Network) communication errors between the engine controller and machine monitoring system. This diagnostic trouble code signals that the ECM is unable to properly send or receive data packets through the communication network that coordinates engine performance with hydraulic functions.

The CAN bus system on the PC210-10 is critical because it allows real-time coordination between the engine's power output and the hydraulic demands of the machine. When communication breaks down, the excavator's intelligent control systems cannot optimize fuel delivery, monitor emissions parameters, or properly regulate engine load. This fault is particularly significant on Komatsu's Dash-10 series machines, which rely heavily on integrated electronic controls for their advanced fuel efficiency and performance characteristics.

Common Symptoms

When Code E-37 is active on your PC210-10, you may experience:

• Check Engine light illuminated on the instrument cluster with simultaneous communication error warnings on the monitor panel
• Erratic engine RPM or failure to respond properly to throttle inputs, especially under hydraulic load
• Loss of monitor functions, including inability to view engine parameters, fuel consumption data, or service intervals on the display
• Intermittent engine derating or limp mode activation, limiting machine performance to protect components
• Hydraulic system inefficiencies, such as slow cycle times or reduced swing/boom speed due to impaired engine-hydraulic coordination

Potential Causes

The most common technical reasons for E-37 appearing on used PC210-10 excavators include:

• Damaged CAN bus wiring harness, particularly at harness routing points near the engine where vibration and heat cause insulation breakdown (check the harness run along the left side of the engine block)
• Corroded or loose connectors at the ECM (located behind the operator cab) or at the junction boxes under the engine hood
• Failed termination resistor in the CAN network, typically a 120-ohm resistor that prevents signal reflection
• ECM internal failure or corrupted software, more common in machines with 8,000+ operating hours
• Voltage irregularities from failing batteries, poor ground connections at the chassis ground point near the battery box, or alternator output issues
• Moisture intrusion into sealed connectors, especially on machines operated in wet conditions without proper connector boot protection

How to Troubleshoot and Fix Code E-37

Step 1: Perform Initial Visual Inspection Begin by inspecting all wiring harnesses between the ECM and the instrument cluster. On used excavators, check specifically for harness wear where cables contact the engine block or frame rails. Look for abraded insulation, pinched wires, or signs of previous repairs with electrical tape. Inspect all connector pins for corrosion (green/white deposits), bent pins, or moisture inside connector housings.

Step 2: Test CAN Bus Continuity and Resistance Using a digital multimeter, disconnect power and measure resistance between CAN-High and CAN-Low wires at the ECM connector (typically pins 32 and 33 on the PC210-10). You should read approximately 60 ohms with both termination resistors in the circuit, or 120 ohms with one terminator. Readings significantly higher suggest an open circuit; readings near zero indicate a short. Check voltage with ignition on, key off: you should see approximately 2.5V on both CAN lines relative to ground.

Step 3: Verify Power Supply and Grounds Confirm the ECM receives proper voltage (typically 24V on Komatsu machines) at the power supply pins. Check ground circuits for resistance; any reading above 0.5 ohms indicates a poor ground requiring cleaning and retightening. On used machines, corrosion at ground points is extremely common—remove, wire brush, and apply dielectric grease.

Step 4: Use Diagnostic Software Connect Komatsu KOMTRAX or compatible diagnostic software (such as the official Komatsu diagnostic tool) to read detailed fault data, including communication error frequency and which modules are dropping offline. This can pinpoint whether the issue is ECM-side, monitor-side, or a specific harness section.

Step 5: Check and Replace Components Systematically If wiring and connections test good, measure the termination resistors individually—they should each read 120 ohms. Replace any defective resistors. For used excavators with persistent issues after these checks, consider ECM replacement, but verify with Komatsu that the replacement ECM is programmed with the correct software version for your machine's serial number range.

Disclaimer: While this guide provides diagnostic direction for Code E-37, CAN bus systems require specific technical knowledge. For used excavators with complex electrical histories or if you're uncomfortable with advanced electrical diagnostics, consult a certified Komatsu technician or qualified heavy equipment electrician to prevent misdiagnosis and unnecessary parts replacement.