What is Komatsu PC110-8M0 Fault Code E-19?

Fault Code E-19 on the Komatsu PC110-8M0 excavator indicates a hydraulic pump control system malfunction, specifically related to the main pump discharge pressure sensor circuit abnormality. This diagnostic trouble code (DTC) is triggered when the machine's Electronic Control Module (ECM) detects voltage readings outside the expected range from the discharge pressure sensor monitoring the hydraulic main pump output.

This fault is critical for the PC110-8M0 because the hydraulic pump control system directly manages engine-pump torque matching, which optimizes fuel efficiency and prevents engine overload. When the ECM cannot accurately read discharge pressure, it may force the excavator into a derate mode to protect internal components. For used excavators, this code often signals sensor degradation or wiring issues common in machines with 3,000+ operating hours.

Common Symptoms

When Code E-19 is active, operators typically experience:

• Warning light illuminated on the instrument panel, often accompanied by error message display
• Reduced hydraulic power across all functions (boom, arm, bucket, swing) as the system enters protective mode
• Intermittent loss of digging force, particularly under heavy loads when discharge pressure fluctuates
• Erratic engine response when operating multiple hydraulics simultaneously due to improper pump-engine coordination
• Sluggish operation during warm-up or first use of the day, which may temporarily clear as components heat up

Potential Causes

The most common technical causes for E-19 in used PC110-8M0 excavators include:

• Discharge pressure sensor failure due to internal component wear, seal deterioration, or contamination from hydraulic fluid degradation
• Wiring harness damage at known rub points near the main pump assembly, where cables contact the engine block during vibration
• Corroded or loose connector pins at the sensor plug, especially on machines operated in wet or coastal environments
• ECM voltage supply issues, including damaged power supply circuits providing reference voltage to the sensor (typically 5V)
• Contaminated hydraulic oil affecting sensor diaphragm accuracy or causing internal sensor clogging
• Previous repair attempts involving aftermarket sensors with incorrect voltage output specifications

How to Troubleshoot and Fix Code E-19

Step 1: Visual Inspection and Connector Verification

Begin by locating the main pump discharge pressure sensor mounted on the hydraulic pump housing (passenger side of the engine compartment). Disconnect the sensor connector and inspect both male and female pins for corrosion, bent terminals, or hydraulic oil contamination. On used excavators, connector seal failure is common—clean contacts with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: Sensor Circuit Testing

Using a digital multimeter (DMM), backprobe the sensor connector with the ignition on, engine off. Verify the ECM supplies approximately 5.0V ±0.25V on the reference voltage wire (consult the PC110-8M0 wiring diagram for pin identification—typically a red or orange wire). Check the ground circuit shows less than 0.5 ohms resistance to chassis ground. Signal voltage should read between 0.5-4.5V depending on system pressure (approximately 1V at rest).

Step 3: Sensor Replacement and Harness Inspection

If voltage readings are outside specifications or the sensor shows internal resistance issues (normal resistance: 250-350 ohms across terminals), replace the discharge pressure sensor with a genuine Komatsu part (Part #: 7861-93-1651 or equivalent). Before installation, thoroughly inspect the wiring harness from sensor to ECM, particularly where it passes along the engine valley and near the turbocharger. Look for wire insulation damage, exposed copper, or heat degradation. Replace damaged sections rather than applying electrical tape, as vibration will cause future failures.

Step 4: System Verification with Diagnostic Software

After repairs, use Komatsu KOMTRAX or compatible diagnostic software (such as Komatsu PC Service Software) to clear the fault code and monitor real-time sensor data. Run the excavator through full hydraulic operations and verify discharge pressure readings correspond to actual system load (typically 200-350 bar during normal operation).

---

Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu PC110-8M0 service manual for complete specifications and safety procedures. If you lack proper diagnostic tools or technical expertise, contact a certified Komatsu dealer or qualified heavy equipment mechanic to prevent further damage to hydraulic or electrical systems.