What is Komatsu PC210LC-10 Fault Code DGH2KB?

Fault Code DGH2KB indicates a DEF (Diesel Exhaust Fluid) quality sensor circuit malfunction in the Komatsu PC210LC-10's aftertreatment system. This code specifically relates to the SCR (Selective Catalytic Reduction) system's ability to monitor DEF concentration and purity. The DEF quality sensor measures the urea concentration in the diesel exhaust fluid tank to ensure proper emissions control and optimal NOx reduction performance.

This fault is critical because the PC210LC-10's Tier 4 Final engine relies on precise DEF quality monitoring to maintain compliance with emissions standards. When the ECM (Engine Control Module) detects abnormal signals from the quality sensor circuit, it triggers DGH2KB and may initiate engine derate protocols to protect the aftertreatment system from damage caused by contaminated or diluted DEF.

Common Symptoms

When fault code DGH2KB is active on your Komatsu PC210LC-10, you may experience:

• Amber warning light illuminated on the instrument cluster with a DEF system icon
• Engine power derate to 75% or lower after a preset grace period (typically 50 operating hours)
• Service reminder messages displayed on the monitor panel requesting immediate attention
• Hesitation or reduced hydraulic performance during high-demand operations due to limited engine output
• Stored fault codes visible through the Komatsu diagnostic system (KOMTRAX or PC-based software)

Potential Causes

The most common technical reasons for DGH2KB appearing on used PC210LC-10 excavators include:

• Contaminated or degraded DEF from prolonged storage or exposure to extreme temperatures
• Failed DEF quality sensor due to crystallization buildup on the sensor probe element
• Corroded or damaged wiring harness connections at the DEF tank, particularly where the harness routes near the tank mounting bracket (known rub point)
• ECM communication errors caused by loose or oxidized connectors in the engine compartment
• Low DEF tank levels triggering false quality readings when the sensor is partially exposed
• Aftermarket or incorrect DEF fluid that doesn't meet ISO 22241 specifications

How to Troubleshoot and Fix Code DGH2KB

Step 1: Initial Inspection and DEF Verification Start by checking the DEF tank level—ensure it's above 25% capacity. Inspect the DEF fluid itself; it should be clear and colorless. If it appears cloudy, yellowish, or has crystalline deposits, drain and replace with fresh ISO 22241-certified DEF. Check the expiration date on your DEF supply, as degraded fluid is common in used excavators with irregular maintenance histories.

Step 2: Sensor and Harness Inspection Access the DEF quality sensor located inside the DEF tank assembly. Using a digital multimeter, check the sensor connector for proper voltage supply (typically 5V reference from ECM) and ground continuity. Inspect the wiring harness from the sensor to the ECM, paying special attention to areas where the harness contacts metal brackets or frame members—chafing and insulation wear are frequent issues on machines with 3,000+ operating hours. Look for green corrosion on connector pins and clean with electrical contact cleaner if present.

Step 3: Component Testing and ECM Diagnostics Connect Komatsu diagnostic software (or compatible J1939 scan tool) to retrieve freeze-frame data and monitor live sensor values. The DEF quality sensor should read between 0.5-4.5V during normal operation. Resistance across the sensor terminals should measure approximately 1,000-3,000 ohms (consult service manual for exact specifications). If readings fall outside parameters, replace the DEF quality sensor assembly. Before installing new components on used equipment, apply dielectric grease to all connectors to prevent future corrosion.

Disclaimer: This guide provides general troubleshooting information for educational purposes. Always consult the official Komatsu service manual for your specific serial number and seek assistance from certified Komatsu technicians for complex repairs. Improper diagnosis or repairs may void warranties or cause equipment damage.