Komatsu PC210-10 Fault Code E-31: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code E-31?

Fault Code E-31 on the Komatsu PC210-10 indicates a malfunction in the hydraulic pump discharge pressure sensor circuit. This code specifically points to abnormal voltage readings from the sensor responsible for monitoring main pump discharge pressure in the excavator's hydraulic system.

The pump discharge pressure sensor is critical for the PC210-10's advanced hydraulic management system. It feeds real-time pressure data to the Engine Control Module (ECM), which adjusts pump output to match workload demands while preventing system over-pressurization. When this sensor circuit fails, the excavator loses critical hydraulic performance optimization, potentially leading to reduced digging force, inefficient fuel consumption, and possible damage to hydraulic components.

Common Symptoms

When Code E-31 is active, operators typically experience:

• Warning light illumination on the monitor panel with hydraulic system alerts
• Reduced hydraulic power during heavy digging or lifting operations
• Erratic or sluggish boom/arm/bucket movements under load
• Engine derate or limited RPM as the ECM enters protective mode
• Intermittent or constant error messages on the multi-information display

Potential Causes

The most common technical failures triggering E-31 on used PC210-10 excavators include:

• Faulty pump discharge pressure sensor (sensor drift or internal failure after 5,000+ operating hours)
• Damaged wiring harness at known rub points near the main hydraulic pump mounting area
• Corroded or moisture-infiltrated connector pins at the sensor or ECM connections
• Open or short circuit in the sensor signal wire between the pump and controller
• Low voltage supply to the sensor (damaged 5V reference circuit from ECM)
• ECM internal fault (rare, but possible in high-hour used machines)

How to Troubleshoot and Fix Code E-31

Step 1: Visual Inspection Begin by inspecting the pump discharge pressure sensor located on the main hydraulic pump assembly. Check for physical damage, oil contamination on the connector, or loose mounting. On used excavators, examine the wiring harness routing for chafing against metal edges, especially where it passes near the pump housing—a common wear point on PC210-10 models.

Step 2: Electrical Testing Using a digital multimeter, verify the sensor receives proper 5-volt reference voltage from the ECM with the ignition on. Measure resistance across the sensor terminals (typical specification: 100-300 ohms at room temperature). Check for continuity in the signal wire from sensor to ECM connector pin, and inspect for short circuits to ground (reading should be infinite resistance).

Step 3: Connector Cleaning and Testing Disconnect the sensor connector and inspect pins for corrosion or bent contacts—extremely common in machines operating in wet or coastal environments. Clean with electrical contact cleaner and apply dielectric grease to prevent moisture re-entry. Clear the code using Komatsu KOMTRAX diagnostic software or compatible scan tool and monitor for recurrence.

Step 4: Component Replacement If electrical tests confirm sensor failure, replace with a genuine Komatsu pump pressure sensor (Part No. 7861-93-1651 or equivalent). For used excavators with high hours (8,000+), consider replacing the entire sensor harness section if insulation shows cracking or brittleness to prevent future failures.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC210-10 service manual and consider professional diagnostic assistance for complex hydraulic system issues. Improper repairs may void warranties or cause safety hazards.