Komatsu PC210LC-10 Fault Code DAFGMC: Meaning and Fix

What is Komatsu PC210LC-10 Fault Code DAFGMC?

Fault code DAFGMC on the Komatsu PC210LC-10 indicates a Diesel After-treatment FilterGage Monitoring Circuit malfunction. This code specifically relates to the Diesel Particulate Filter (DPF) pressure sensor circuit, which monitors differential pressure across the DPF to determine filter loading and regeneration status.

The DPF system is critical to this Tier 4 Final compliant engine's emissions control. The Electronic Control Module (ECM) relies on accurate pressure readings to initiate regeneration cycles and protect the DPF from catastrophic blockage. When the monitoring circuit fails, the ECM cannot properly manage the after-treatment system, potentially leading to engine derate or shutdown to prevent costly DPF damage.

Common Symptoms

When code DAFGMC is active on your PC210LC-10, you may experience:

• DPF warning lamp illuminated on the instrument cluster, possibly accompanied by engine derate icon
• Forced regeneration requests occurring more frequently than normal or failing to complete
• Power reduction mode (engine derate) limiting machine productivity, typically 25-40% power loss
• Intermittent error messages on the monitor display related to exhaust system performance
• Abnormal regeneration behavior, including regeneration cycles that won't initiate despite high soot loading

Potential Causes

The DAFGMC fault code typically stems from these common issues in used excavators:

• Failed DPF differential pressure sensor due to carbon buildup, heat exposure, or sensor element deterioration
• Damaged wiring harness between the pressure sensor and ECM, particularly at chassis flex points near the exhaust system
• Corroded or loose electrical connectors on the pressure sensor, especially on machines operating in wet or corrosive environments
• Blocked or kinked pressure sensing hoses connecting the sensor to the DPF inlet/outlet pressure taps
• ECM communication fault or internal ECM circuit damage (less common)
• Aftermarket exhaust modifications or poorly executed DPF repairs affecting sensor mounting or hose routing

How to Troubleshoot and Fix Code DAFGMC

Step 1: Visual Inspection Begin by locating the DPF differential pressure sensor mounted on the exhaust system (typically on the left side near the DPF canister). Inspect the sensor connector for corrosion, bent pins, or moisture infiltration. Check both pressure sensing hoses for cracks, kinks, or carbon blockage. On used excavators, pay special attention to heat-damaged wiring or hoses that have hardened from repeated regeneration cycles.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals (typical specification: 1.5-3.0 kΩ at 20°C, consult service manual). Check supply voltage at the harness connector with ignition on (should read approximately 5V reference). Verify ground circuit continuity between sensor ground pin and chassis ground (should read <1Ω resistance).

Step 3: Pressure Line Testing Remove both pressure sensing hoses from the sensor and physically inspect for blockage. These small-diameter hoses frequently clog with carbon particulates. Blow compressed air (regulated to 30 PSI max) through the lines to clear blockages. Verify hoses are properly routed without sharp bends that restrict airflow.

Step 4: Diagnostic Software Verification Connect Komatsu KOMTRAX or compatible diagnostic software to monitor live sensor data. With engine running, pressure readings should show differential change during varying engine loads. Erratic, frozen, or out-of-range values confirm sensor replacement is necessary.

Step 5: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu pressure sensor (part number specific to PC210LC-10). After-market sensors frequently cause repeat failures on emissions-critical circuits. Clear fault codes, perform a manual regeneration cycle, and verify proper system operation.

Important for Used Equipment: Always inspect the entire harness routing from sensor to ECM, especially at known rub points along the chassis rails and near the turbocharger. Previous repairs may have left harnesses inadequately secured, leading to vibration damage.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and follow proper safety procedures. For persistent issues or if you're unfamiliar with heavy equipment electronics, consult a certified Komatsu technician to avoid costly misdiagnosis or warranty implications.