What is Komatsu PC110-8M0 Fault Code D862KA?

Fault Code D862KA indicates an abnormal signal detected in the diesel particulate filter (DPF) differential pressure sensor circuit on the Komatsu PC110-8M0 excavator. This code triggers when the Engine Control Module (ECM) receives voltage readings outside the expected range from the DPF differential pressure sensor, which monitors exhaust backpressure across the diesel particulate filter.

This sensor is critical for the PC110-8M0's Tier 4 Final emissions system. It continuously measures the pressure difference between the inlet and outlet of the DPF, allowing the ECM to determine filter loading and initiate regeneration cycles. When D862KA activates, the excavator may enter derate mode to protect the engine from excessive backpressure or incomplete regeneration, directly impacting productivity and fuel efficiency.

Common Symptoms

When fault code D862KA is active, operators typically experience:

• Check Engine Light illuminated on the instrument panel with possible DPF warning indicator
• Power derate or limited engine RPM, especially under load during digging operations
• Frequent or failed regeneration cycles, with the regeneration light cycling abnormally
• Black or excessive exhaust smoke due to improper DPF system monitoring
• Error messages on the monitor display specifically referencing exhaust system faults

Potential Causes

The most common technical reasons for D862KA on used PC110-8M0 excavators include:

• Failed DPF differential pressure sensor due to carbon buildup or internal sensor element degradation
• Damaged wiring harness or corroded connectors, particularly where the harness routes near the exhaust manifold and experiences heat cycling
• Clogged or broken pressure sensing tubes connecting the sensor to the DPF inlet/outlet ports
• ECM software issues or calibration errors following previous repairs
• Shorted or open circuit in the sensor signal wires (common rub points exist near the turbocharger on this model)
• Physically damaged DPF housing allowing exhaust leaks that affect pressure readings

How to Troubleshoot and Fix Code D862KA

Step 1: Visual Inspection Begin with a thorough inspection of the differential pressure sensor (located on the left side of the engine near the DPF canister). Check all wiring connectors for corrosion, bent pins, or moisture intrusion—critical on used machines. Inspect the rubber pressure sensing tubes for cracks, carbon blockages, or disconnection.

Step 2: Electrical Testing Using a digital multimeter, check sensor supply voltage at the connector (should read approximately 5 volts with key on, engine off). Measure sensor signal wire resistance to ground (should show open circuit/infinite resistance). Check for proper ground continuity on the sensor ground wire (less than 1 ohm resistance to chassis ground).

Step 3: Sensor Output Verification With the engine running at idle, use Komatsu diagnostic software (KOMTRAX or dealer-level scan tool) to monitor live differential pressure sensor values. Readings should show minimal pressure difference at idle (typically 0.5-2.0 kPa). Compare actual sensor output voltage (typically 0.5-4.5V range) against expected values in the service manual.

Step 4: Component Replacement If electrical tests pass but the sensor reading remains erratic, replace the DPF differential pressure sensor (Komatsu part number specific to PC110-8M0). On used excavators, simultaneously replace the pressure sensing tubes, as carbon deposits often render them unreliable. Clear codes and perform a manual regeneration cycle to verify repair.

For used excavators specifically: Always inspect harness routing for evidence of previous repairs, zip-tie modifications, or heat damage from exhaust components before condemning electronic parts.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnostic assistance for complex emissions system repairs. Improper DPF system repairs may violate emissions regulations.