What is Komatsu PC210-10 Fault Code DGH2KB?

Fault Code DGH2KB on the Komatsu PC210-10 excavator indicates a DEF (Diesel Exhaust Fluid) pressure sensor circuit malfunction within the aftertreatment system. This code specifically points to an abnormal voltage signal detected by the Engine Control Module (ECM) from the DEF pressure sensor, which monitors the pressure of diesel exhaust fluid being delivered to the Selective Catalytic Reduction (SCR) system.

This fault affects the emission control system critical to Tier 4 Final compliance. The DEF pressure sensor ensures proper urea solution injection into the exhaust stream for NOx reduction. When the ECM cannot accurately read DEF pressure, it may limit engine performance or trigger derate modes to protect emissions compliance and prevent SCR system damage. For used PC210-10 excavators, this code commonly appears due to sensor degradation, crystallized DEF contamination, or wiring issues from years of vibration and environmental exposure.

Common Symptoms

• Yellow or amber warning light illuminated on the instrument cluster, often accompanied by a check engine light
• Engine power derate after a certain grace period, reducing maximum RPM and hydraulic power output
• Poor fuel economy due to inefficient aftertreatment system operation
• Excessive DEF consumption or zero DEF usage reported by the monitoring system
• Hesitation or reduced responsiveness during heavy digging or lifting operations

Potential Causes

The most common technical causes for DGH2KB on used Komatsu PC210-10 excavators include:

• Failed DEF pressure sensor due to internal component degradation or crystallized urea contamination on the sensor element
• Damaged wiring harness between the sensor and ECM, particularly at known rub points near the DEF tank mounting bracket and frame rails
• Corroded or loose electrical connectors at the sensor or ECM interface, often caused by moisture intrusion or DEF leakage
• Open or short circuit in the sensor signal wire (typically pin 1 or pin 2 of the sensor connector)
• Low system voltage or poor grounding affecting sensor reference voltage supplied by the ECM
• ECM software calibration issues requiring firmware updates, especially on early production model years

How to Troubleshoot and Fix Code DGH2KB

Step 1: Visual Inspection Begin by inspecting the DEF pressure sensor located on the DEF supply line near the dosing unit. Check for physical damage, DEF crystallization around the sensor body, and connector integrity. Examine the wiring harness from sensor to ECM for abrasion, pinching, or heat damage—pay special attention to areas where harnesses contact frame members or move with engine vibration.

Step 2: Electrical Testing Using a digital multimeter, perform a connector pin-out test with the ignition off. Check for 5-volt reference voltage from the ECM at the sensor connector (typically pin 1). Measure sensor ground continuity (pin 3) to ensure less than 1 ohm resistance to chassis ground. Test signal wire resistance (pin 2) from sensor connector to ECM connector—it should read less than 5 ohms.

Step 3: Sensor Verification With the sensor connected and ignition on (engine off), use Komatsu KOMTRAX diagnostic software or an aftermarket scan tool to monitor live DEF pressure sensor voltage. Normal readings range from 0.5 to 4.5 volts depending on system pressure. Readings stuck at 0V or 5V indicate sensor failure or wiring faults. For used excavators, remove and inspect the sensor for DEF crystal buildup; clean carefully with warm water if contaminated.

Step 4: Component Replacement If voltage tests confirm sensor failure, replace with a genuine Komatsu DEF pressure sensor (part number 6754-81-9110 or equivalent). Before installing, flush the DEF supply line to remove any crystallized contamination. Apply dielectric grease to connector pins to prevent future corrosion—critical for used machines with aging electrical systems.

Step 5: Clear Code and Verify After repairs, clear the fault code using diagnostic software and perform a regeneration cycle to verify proper SCR system operation. Monitor DEF pressure values under various engine loads to confirm stable readings.

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Disclaimer: This guide provides general troubleshooting information for experienced diesel mechanics. Always consult the official Komatsu PC210-10 service manual and safety procedures. If you lack proper diagnostic tools or experience with high-pressure fuel and emissions systems, seek assistance from a certified Komatsu technician or qualified heavy equipment repair facility.