What is Komatsu PC210LC-8M0 Fault Code DA22KK?

Fault Code DA22KK indicates a malfunction in the DEF (Diesel Exhaust Fluid) pump system, specifically related to the pump motor circuit or pump performance failure within the Selective Catalytic Reduction (SCR) aftertreatment system. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects abnormal current draw, insufficient DEF delivery pressure, or complete pump motor failure during SCR system operation.

The SCR system on the Komatsu PC210LC-8M0 is critical for meeting Tier 4 Final emissions standards. The DEF pump supplies urea solution to the decomposition chamber, where it converts harmful NOx emissions into harmless nitrogen and water. When DA22KK activates, the SCR system cannot function properly, potentially causing the machine to enter derate mode or fail emissions compliance, making this code particularly critical for used excavators operating under strict environmental regulations.

Common Symptoms

• Amber or red DEF warning lamp illuminated on the instrument cluster with possible engine derate notification
• Reduced engine power (derate to 75% or lower) after a predetermined timer expires, typically following several hours of operation
• SCR system disabled message displayed on the monitor panel with associated fault code
• Audible warning alarm accompanying the visual indicators, especially when approaching derate conditions
• Increased DEF consumption or no DEF consumption at all, depending on whether the pump runs continuously or fails completely

Potential Causes

The most common technical causes for DA22KK on used PC210LC-8M0 excavators include:

• DEF pump motor failure due to crystallized urea contamination inside the pump housing (common in machines with contaminated or low-quality DEF)
• Electrical connector corrosion at the DEF pump harness connection, particularly on machines operating in coastal or high-humidity environments
• Wiring harness damage along the frame rail near the DEF tank mounting bracket—a known rub point on this model
• DEF pump relay failure within the main electrical panel under the operator's cab
• ECM internal fault related to the DEF pump driver circuit (less common but possible in high-hour machines)
• Contaminated or frozen DEF causing pump mechanical seizure or check valve blockage

How to Troubleshoot and Fix Code DA22KK

Step 1: Initial Visual Inspection Begin by inspecting the DEF pump assembly mounted on the DEF tank. Check all electrical connectors for corrosion, moisture intrusion, or loose pins. On used excavators, pay particular attention to the harness routing along the left-side frame rail where it passes near hydraulic lines—this is a known wear point on PC210LC-8M0 models. Clean any corrosion using electrical contact cleaner and dielectric grease.

Step 2: Electrical Circuit Testing Using a digital multimeter, perform voltage and resistance checks. With ignition on (engine off), verify 12V supply voltage at the DEF pump connector (typically pin 1). Check ground circuit continuity (should read less than 0.5 ohms to chassis ground). Disconnect the pump connector and measure pump motor winding resistance between motor terminals—typical specification is 3-6 ohms. Values outside this range indicate pump motor failure.

Step 3: Diagnostic Software Analysis Connect Komatsu KOMTRAX diagnostic software or compatible scan tool to access live data. Monitor DEF pump current draw during commanded operation (should be 4-8 amps during normal operation). Check DEF pressure sensor values—normal operating pressure is 60-87 psi. If current exceeds 12 amps or pressure remains at zero during pump activation, the pump has likely failed mechanically.

Step 4: Component Replacement and Validation If testing confirms pump failure, replacement is necessary. When working on used excavators, always drain and inspect the DEF tank for contamination or crystallization before installing a new pump. Replace the DEF filter/suction strainer simultaneously. After installation, perform a SCR system purge procedure using diagnostic software to remove air from the lines. Clear codes and perform a DEF pump functional test to verify proper operation before returning to service.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu service manual for your specific machine serial number and software version. If unfamiliar with high-pressure SCR systems or diagnostic procedures, consult a certified Komatsu technician to prevent costly misdiagnosis or component damage.