What is Komatsu PC200-10 Fault Code CA2555?

Fault Code CA2555 indicates a malfunction in the fuel injector circuit for cylinder #5, specifically a detected open circuit or abnormal resistance in the injector control wiring. This diagnostic trouble code (DTC) is generated by the Engine Control Module (ECM) when it cannot properly energize the fuel injector solenoid for the fifth cylinder due to electrical discontinuity or resistance values outside manufacturer specifications.

For the Komatsu PC200-10 equipped with the SAA6D107E-3 engine, this code is critical because it directly affects fuel delivery precision and combustion efficiency. The common rail fuel injection system relies on precise ECM control of each injector's solenoid valve. When cylinder #5 cannot receive proper fuel metering commands, engine performance, emissions compliance, and overall reliability are compromised. Left unaddressed, this fault can lead to unburned fuel contaminating engine oil and potential damage to the diesel particulate filter (DPF).

Common Symptoms

When CA2555 is active on your PC200-10, operators typically experience:

• Engine warning lamp illuminated on the instrument cluster with reduced power output
• Rough idle and noticeable vibration due to cylinder #5 misfiring or not firing
• Black or white exhaust smoke indicating incomplete combustion
• Increased fuel consumption as the ECM attempts to compensate for the missing cylinder
• Potential engine derate mode limiting machine RPM to 1,500-1,800 to prevent further damage

Potential Causes

The most common technical reasons for CA2555 appearing on used excavators include:

• Damaged injector harness at the valve cover connection point where vibration causes wire chafing
• Failed fuel injector solenoid coil in the #5 injector (resistance typically should read 0.3-0.6 ohms)
• Corroded or loose connector pins at the injector plug due to moisture intrusion or age
• Chafed wiring along the harness routing near the cylinder head, a known wear point on PC200-10 models
• ECM internal driver circuit failure (less common but possible in high-hour machines)
• Previous repair attempts using incorrect harness routing causing recurring failures

How to Troubleshoot and Fix Code CA2555

Step 1: Visual Inspection of Harness and Connections Begin by removing the engine covers and inspecting the injector harness routing to cylinder #5. Check for obvious physical damage, burns, or wire insulation wear especially where the harness contacts the valve cover or brackets. For used excavators, pay special attention to connector corrosion—clean with electrical contact cleaner and verify pin tension.

Step 2: Measure Injector Resistance Disconnect the injector connector at cylinder #5. Using a quality digital multimeter, measure resistance across the injector solenoid terminals. Specification should be approximately 0.4 ohms ± 0.1 ohms at room temperature. Also check for shorts to ground by measuring from each terminal to the injector body (should read infinite resistance/open circuit).

Step 3: Perform Harness Continuity and Voltage Tests With the injector disconnected and ignition ON (engine off), check for battery voltage (approximately 24V on PC200-10) at the harness connector using your multimeter. Then check continuity from the harness connector back to the ECM pins using wiring diagrams from Komatsu's diagnostic software (KOMTRAX Plus or Komatsu Diagnostic System). Resistance should be less than 5 ohms for the entire circuit.

Step 4: Inspect ECM Connections and Clear Code If harness and injector test within specifications, inspect the ECM connectors for corrosion or damaged pins. After repairs, clear the fault code using diagnostic software and perform a injector cut-out test to verify cylinder #5 now responds properly. Monitor for code recurrence during a 30-minute operational test.

Critical Note for Used Machines: Before replacing the injector (cost: $800-1,200), always verify harness integrity. Approximately 70% of CA2555 codes on used PC200-10 excavators result from harness wear rather than injector failure.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific serial number and consult with a certified Komatsu technician for complex diagnostics. Improper repairs to fuel injection systems can cause severe engine damage.