Komatsu PC210-10 Fault Code DAFGMC: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code DAFGMC?

Fault code DAFGMC on the Komatsu PC210-10 excavator indicates a Diesel After-treatment Fuel Gas Mixture Control malfunction, specifically related to the dosing system that injects fuel into the exhaust stream for diesel particulate filter (DPF) regeneration.

This fault code triggers when the electronic control module (ECM) detects an abnormal deviation in the air-fuel mixture entering the diesel oxidation catalyst (DOC) during active regeneration cycles. The PC210-10 uses a sophisticated seventh injector system mounted in the exhaust manifold to inject diesel fuel for raising exhaust temperatures during DPF regeneration. When this dosing system fails to maintain proper fuel atomization or delivery rates, the DAFGMC code activates to prevent potential damage to expensive aftertreatment components.

This is critical for the PC210-10's SAA6D107E-3 engine because improper dosing can cause incomplete regeneration, leading to excessive soot accumulation, turbocharger damage, or catastrophic DPF failure—repairs that can exceed $8,000-$12,000 on used equipment.

Common Symptoms

• Amber or red warning light illuminated on the instrument cluster with simultaneous DPF lamp activation
• Engine power derate to 75-80% of normal output, limiting machine productivity during critical operations
• Frequent automatic regeneration attempts occurring every 2-3 hours instead of the normal 8-12 hour intervals
• Excessive white or blue smoke from the exhaust stack during regeneration cycles
• Fuel consumption increase of 15-25% due to inefficient regeneration processes

Potential Causes

The most frequent technical failures triggering DAFGMC on used PC210-10 excavators include:

• Seventh injector (dosing injector) failure due to carbon buildup or internal coking after 4,000-6,000 operating hours
• Wiring harness chafing at the frame rail near the fuel tank where the dosing pump harness passes—a known wear point on 2014-2018 models
• Dosing fuel pump degradation caused by water contamination in the dedicated dosing fuel tank
• Exhaust gas temperature (EGT) sensor drift providing incorrect feedback to the ECM for mixture calculations
• ECM calibration corruption particularly in machines that have experienced electrical system voltage spikes or aftermarket accessory installations
• Clogged dosing fuel filter restricting fuel flow to the seventh injector assembly

How to Troubleshoot and Fix Code DAFGMC

Step 1: Connect Diagnostic Equipment Use Komatsu KOMTRAX Plus or compatible PC-based diagnostic software (JPRO, Nexiq) with the 6-pin or 9-pin diagnostic connector located beneath the operator seat. Record all active and inactive fault codes, and check freeze frame data for dosing pressure values (should read 450-550 kPa during active dosing).

Step 2: Inspect Dosing System Components Physically inspect the seventh injector mounted on the exhaust manifold turbo inlet side. Check for carbon deposits blocking the nozzle tip or fuel leakage at threaded connections. On used excavators with 5,000+ hours, remove the injector and bench-test spray pattern—it should produce a fine 60-degree conical mist, not dripping or streaming fuel.

Step 3: Test Dosing Pump and Electrical Circuit Locate the dosing fuel pump (small 12V pump near the main fuel tank). Disconnect the electrical connector and perform a voltage test: key on, engine off should show 0V; during active regeneration should read 12-14V. Use a multimeter to check pump resistance (should be 4-6 ohms). Inspect the dedicated dosing fuel supply line for kinks or restrictions.

Step 4: Verify Wiring Harness Integrity The PC210-10 has a problematic harness routing point where the dosing injector harness crosses the right-side frame rail approximately 18 inches forward of the fuel tank. Inspect for wire insulation wear, exposed copper, or corrosion on connector pins (common failure point at 6,000-8,000 hours on used machines). Repair with OEM-spec weather-resistant connectors, not standard crimp terminals.

Step 5: Check EGT Sensors and Calibration Test both upstream and downstream exhaust gas temperature sensors with a digital multimeter. At 20°C ambient, resistance should read approximately 2,200-2,800 ohms. Compare live data readings during regeneration—upstream EGT should reach 550-620°C. If sensors test within specification but code persists, the ECM may require flash reprogramming with updated Komatsu calibration files (TSB reference KMT-2017-0842 addresses DAFGMC calibration issues).

Step 6: Inspect Aftertreatment Components For persistent codes on used excavators, perform a backpressure test on the DPF using the diagnostic port. Readings exceeding 4.5 kPa at rated RPM indicate excessive soot loading that prevents proper regeneration. Clean or replace the DPF and DOC as needed before continuing electrical diagnostics.

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Professional Disclaimer: Diesel aftertreatment systems involve high-temperature exhaust components and pressurized fuel systems. This guide provides general diagnostic direction, but complex ECM programming and component replacement should be performed by Komatsu-certified technicians with proper safety equipment. Improper repairs to emissions systems may violate EPA regulations and void equipment warranties. Always consult the official Komatsu PC210-10 Shop Manual (SEBM056808) for model-specific torque specifications and safety procedures.