What is Kobelco SK135SR-2 Fault Code P0606?

Fault Code P0606 on the Kobelco SK135SR-2 excavator indicates a PCM/ECM Processor Internal Performance Error. This critical diagnostic trouble code (DTC) signals that the Engine Control Module (ECM) has detected an internal malfunction within its own processing unit or memory circuits.

The ECM is the brain of your excavator's engine management system, controlling fuel injection timing, air-fuel ratios, emissions systems, and sensor data processing. When the processor detects inconsistencies in its own calculations or memory storage, it triggers P0606 as a self-protection measure. For the SK135SR-2's Hino J05E engine, this code is particularly serious because it can lead to unexpected shutdowns, incorrect fuel delivery, and potential damage to downstream components if ignored.

Common Symptoms

• Check Engine Light (CEL) illuminated continuously on the instrument panel
• Erratic engine performance including unexpected RPM fluctuations or rough idling
• Engine derate mode where maximum power output is limited to protect components
• Intermittent no-start conditions or sudden engine stalling during operation
• Unresponsive throttle input or delayed response to operator commands

Potential Causes

The P0606 code on used Kobelco SK135SR-2 excavators typically stems from several age-related and environmental factors:

• ECM internal circuit failure due to component aging, heat stress, or voltage spikes
• Corroded or damaged ECM connectors caused by moisture intrusion or vibration damage
• Faulty power supply voltage from weak batteries, failing alternator, or corroded ground connections
• Software corruption within the ECM memory, particularly common after improper jump-starting procedures
• Physical ECM damage from hydraulic fluid leaks onto the control module housing
• Aftermarket modifications or incompatible software updates that conflict with factory programming

How to Troubleshoot and Fix Code P0606

Step 1: Verify Power Supply and Grounds Using a digital multimeter, check battery voltage (should be 12.5-13V engine off, 13.5-14.5V running). Inspect all ground connections at the ECM, especially those prone to corrosion on used machines. Clean and tighten ground straps on the frame rail and engine block.

Step 2: Inspect ECM Connectors and Harness Disconnect the ECM harness connectors and carefully inspect pins for corrosion, bent terminals, or moisture. On used SK135SR-2 models, check the harness routing near the hydraulic pump where wiring chafing commonly occurs. Apply dielectric grease to cleaned connections.

Step 3: Perform ECM Diagnostic Test Connect Kobelco-specific diagnostic software (or compatible J1939 scanner) to read freeze frame data and verify if P0606 is current or stored. Clear codes and monitor for immediate return—if the code returns instantly without cranking, the ECM likely requires replacement.

Step 4: Check for Voltage Spikes Test the alternator output for abnormal voltage spikes (above 15V) that can damage ECM circuits. Replace the voltage regulator if readings are unstable. For used excavators, verify no aftermarket accessories are creating electrical interference.

Step 5: ECM Replacement Considerations If all external factors check out, the ECM internal processor has likely failed. Source a replacement ECM with matching part numbers, noting that used excavator ECMs often require reprogramming with machine-specific calibration files by a Kobelco dealer or qualified technician.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Kobelco service manual for your specific serial number and seek professional assistance for ECM replacement and programming procedures.