What is Komatsu PC215-10MO Fault Code DAFOMC?

Fault Code DAFOMC on the Komatsu PC215-10MO excavator indicates a Diesel After-treatment Fuel Outlet Metering Control malfunction within the emissions control system. This code specifically points to an issue with the diesel injection dosing valve that meters fuel into the Diesel Particulate Filter (DPF) regeneration system.

This code affects the after-treatment system, which manages exhaust emissions by burning off accumulated soot in the DPF. The ECM (Engine Control Module) monitors the dosing valve's performance to ensure precise fuel delivery for regeneration cycles. When the system detects incorrect metering, abnormal voltage, or mechanical failure in the fuel outlet control circuit, it triggers DAFOMC. For the PC215-10MO with stringent Tier 4 Final emissions compliance, this fault can severely impact both performance and regulatory compliance, making immediate diagnosis essential.

Common Symptoms

• DPF regeneration failure with continuous regeneration requests or inability to complete regeneration cycles
• Engine power derate or limited operating mode, restricting maximum RPM and hydraulic performance
• Amber or red warning lights on the instrument cluster, specifically the DPF or emissions system indicators
• Increased fuel consumption due to inefficient after-treatment operation
• Black or excessive exhaust smoke during attempted regeneration cycles

Potential Causes

Dosing valve electrical failure is the primary culprit, especially in used machines where connector pins corrode from heat exposure and exhaust moisture. The wiring harness routing near the exhaust system creates a known rub point where insulation wears through after 5,000+ operating hours.

Clogged dosing injector nozzle from poor fuel quality or contamination prevents accurate fuel metering. ECM communication errors may result from software corruption or failed control circuits within the module itself.

On used PC215-10MO excavators, connector corrosion at the dosing valve plug is extremely common due to its proximity to the DPF. Failed pressure sensors in the after-treatment fuel supply line can also trigger this code. Relay failures in the dosing control circuit should not be overlooked in higher-hour machines.

How to Troubleshoot and Fix Code DAFOMC

Step 1: Connect Komatsu Diagnostic Software Use KOMTRAX or compatible diagnostic software to verify active and pending codes. Check freeze frame data for voltage readings and operational conditions when the fault occurred.

Step 2: Inspect Dosing Valve Wiring and Connectors Physically examine the dosing valve harness for wear, especially where it routes near hot exhaust components. Disconnect the connector and inspect pins for corrosion, discoloration, or bent contacts. Clean with electrical contact cleaner and apply dielectric grease.

Step 3: Test Dosing Valve Resistance and Supply Voltage Using a digital multimeter, measure resistance across the dosing valve terminals (typically 3-6 ohms). Check for 12V supply voltage at the connector with ignition on. Verify ground circuit continuity to chassis.

Step 4: Inspect After-treatment Fuel Supply System Check fuel supply pressure to the dosing system (consult service manual for specifications, typically 30-50 PSI). Examine the fuel filter and supply lines for restrictions or contamination.

Step 5: Replace Failed Components If electrical values are out of specification, replace the dosing valve assembly. For used excavators, always replace associated O-rings and seals. Clear codes, perform a manual regeneration cycle, and monitor system performance.

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Disclaimer: This guide provides general diagnostic procedures. Always consult the official Komatsu service manual for your specific machine serial number and software version. Complex emissions system repairs may require certified technician intervention and specialized calibration equipment.