Komatsu PC800SE-8R Fault Code E0EDAFRMC: Complete Diagnostic Guide

What is Komatsu PC800SE-8R Fault Code E0EDAFRMC?

Fault Code E0EDAFRMC indicates an Aftertreatment Fuel Rate Monitoring Circuit malfunction in the Komatsu PC800SE-8R excavator's diesel exhaust system. This code specifically relates to the Diesel Particulate Filter (DPF) regeneration system, where the Engine Control Module (ECM) detects an abnormal fuel injection rate during the active regeneration process.

The PC800SE-8R utilizes a sophisticated aftertreatment system that periodically injects diesel fuel into the exhaust stream to burn off accumulated soot in the DPF. When the fuel rate monitoring circuit fails to report accurate data or operates outside specified parameters, the ECM triggers this fault code. This is critical because improper regeneration can lead to DPF clogging, reduced engine performance, and potential damage to expensive aftertreatment components—a significant concern for used excavator owners facing costly repairs.

Common Symptoms

When fault code E0EDAFRMC is active, operators typically experience:

• Amber or red warning light illuminated on the instrument cluster, specifically the DPF or engine malfunction indicator
• Reduced engine power (derate mode) limiting machine performance to 70-80% of normal output
• Failed automatic regeneration cycles, causing the DPF to become increasingly clogged
• Excessive black or white smoke from the exhaust during attempted regeneration
• Frequent regeneration requests or inability to complete regeneration cycles

Potential Causes

The most common technical causes for this fault code include:

• Faulty aftertreatment fuel injector (seventh injector) with clogged nozzle or failed solenoid
• Damaged wiring harness between the ECM and aftertreatment fuel injector, particularly at flex points near the engine mount
• Corroded or loose electrical connectors at the fuel injector or ECM—extremely common in used excavators with 5,000+ hours
• Failed fuel pressure sensor in the aftertreatment fuel supply line
• ECM software corruption or outdated calibration files
• Contaminated diesel fuel causing injector deposits and flow restrictions

How to Troubleshoot and Fix Code E0EDAFRMC

Step 1: Connect Diagnostic Software Use Komatsu KOMTRAX or compatible diagnostic software to retrieve freeze frame data. Check the fuel rate values during the fault occurrence and compare against factory specifications (typically 0.5-2.0 liters/hour during regeneration).

Step 2: Inspect Wiring and Connectors Physically examine the aftertreatment fuel injector harness from the ECM to the injector. On used excavators, check for harness wear at the engine firewall pass-through and near exhaust components where heat damage occurs. Use a multimeter to verify continuity (should read <5 ohms) and check for shorts to ground (should read >10k ohms).

Step 3: Test Aftertreatment Fuel Injector Disconnect the injector and measure solenoid resistance (typically 2-4 ohms at 20°C). Inspect the injector nozzle for carbon buildup—common in machines with irregular regeneration history. Remove and bench-test the injector if possible.

Step 4: Verify Fuel Supply Pressure Check the aftertreatment fuel pressure sensor output (should read 300-500 kPa during regeneration). Replace the fuel filter if contamination is suspected, as this frequently affects used equipment.

Step 5: Clear Code and Monitor After repairs, clear the fault code and perform a forced regeneration using diagnostic software to verify proper fuel rate monitoring. Monitor for code recurrence over several operating cycles.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.