What is Komatsu PC300-7 Fault Code E116?

Komatsu PC300-7 Fault Code E116 indicates a malfunction in the hydraulic pump discharge pressure sensor circuit, specifically a voltage signal that is out of the normal operating range. This code is triggered when the Engine Control Module (ECM) detects abnormal electrical readings from the pressure sensor that monitors main pump output pressure, which is critical for proper hydraulic system operation and load-sensing control.

The hydraulic pump discharge pressure sensor plays a vital role in the PC300-7's advanced hydraulic system by providing real-time pressure data to the ECM. This information allows the controller to optimize fuel injection, engine speed, and pump displacement for efficient operation under varying loads. When this sensor circuit fails, the machine loses its ability to properly manage hydraulic demand, potentially leading to reduced performance and increased fuel consumption.

Common Symptoms

• Yellow engine warning light illuminated on the instrument panel with code E116 displayed on the monitor
• Reduced hydraulic power or sluggish arm, boom, and bucket movements, particularly under heavy loads
• Intermittent loss of fine control during precision digging or grading operations
• Engine failing to respond properly to hydraulic demand (no automatic RPM increase under load)
• Fuel consumption increase due to inefficient pump control and constant high-idle operation

Potential Causes

The most common causes of E116 on used PC300-7 excavators include:

• Faulty hydraulic pump discharge pressure sensor (internal component failure common after 8,000+ operating hours)
• Damaged or corroded wiring harness between the sensor and ECM, especially near the pump mounting area where vibration and heat cause wire insulation breakdown
• Loose or corroded electrical connector at the sensor or ECM (corrosion is prevalent in machines operated in wet or coastal environments)
• Sensor connector pin corrosion or bent pins causing intermittent contact
• ECM internal fault (less common, but possible in high-hour machines with electrical system history)
• Voltage supply issues from the main machine harness providing power to the sensor circuit

How to Troubleshoot and Fix Code E116

Step 1: Visual Inspection Begin by locating the hydraulic pump discharge pressure sensor mounted on the main hydraulic pump housing. Inspect the sensor connector for obvious damage, corrosion (especially green oxidation on pins), oil contamination, or loose connections. On used excavators, check the entire wiring harness route from sensor to ECM for rubbing points, crushed wires, or heat damage near the exhaust manifold and hydraulic lines.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and measure the supply voltage from the ECM (should read approximately 5 volts with ignition on). Next, measure sensor resistance across its terminals (typically 200-400 ohms when cold; consult service manual for exact specifications). Check for continuity in all three wires (signal, ground, and power supply) between the sensor connector and ECM connector.

Step 3: Signal Testing and Sensor Replacement With the engine running (if safe), use Komatsu diagnostic software (KOMTRAX or compatible scan tool) to monitor live sensor voltage output. Normal operating voltage should range between 0.5-4.5 volts depending on hydraulic pressure. If voltage remains fixed, fluctuates erratically, or shows out-of-range readings with known good wiring, replace the pressure sensor (Komatsu part number 7861-93-1650 or equivalent). For used machines, always apply dielectric grease to connector pins during reassembly to prevent future corrosion.

Step 4: Clear Code and Verify After repairs, clear the fault code using diagnostic software and operate the machine through various load conditions for at least 30 minutes to verify the repair. Monitor for code recurrence.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC300-7 service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may lead to further damage or safety hazards.