Sumitomo SH80-6B Fault Code P1605-2: Complete Diagnostic Guide

What is Sumitomo SH80-6B Fault Code P1605-2?

Fault Code P1605-2 indicates a Misfire Detected on Cylinder #2 with moderate severity level in the Sumitomo SH80-6B excavator's engine control system. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects irregular combustion patterns or incomplete firing in the second cylinder through crankshaft position sensor data and engine speed fluctuations.

This fault code is critical for the SH80-6B's performance because cylinder misfires directly impact fuel efficiency, hydraulic system performance, and overall engine longevity. The Isuzu diesel engine powering this model relies on balanced combustion across all cylinders to maintain proper torque delivery for hydraulic pump operation. Ignoring this code can lead to increased diesel particulate filter (DPF) clogging, catalytic converter damage, and accelerated engine wear.

Common Symptoms

When P1605-2 is active on your SH80-6B, operators typically experience:

• Rough idle with noticeable engine vibration, especially when hydraulics are not engaged
• Check Engine Light (CEL) illuminated on the instrument cluster with possible engine derate mode activation
• Loss of power during digging or lifting operations, particularly under heavy loads
• Increased black or white smoke from the exhaust during acceleration
• Poor fuel economy with noticeable increase in diesel consumption compared to normal operation

Potential Causes

The most common technical causes for P1605-2 on used SH80-6B excavators include:

• Faulty fuel injector on cylinder #2 (common wear item after 5,000+ operating hours)
• Low compression in cylinder #2 due to worn piston rings, valve seats, or head gasket failure
• Damaged injector wiring harness or connector corrosion (check harness routing near engine mount where vibration causes wear)
• Clogged fuel filter or contaminated diesel fuel affecting injector spray pattern
• Failed glow plug on cylinder #2 preventing proper cold-start combustion
• ECM software calibration issues or corrupted engine parameters (less common but possible on older machines)

How to Troubleshoot and Fix Code P1605-2

Step 1: Perform Visual Inspection Start by inspecting the fuel injector harness and connector for cylinder #2. On used excavators, check for wire chafing where the harness contacts the valve cover or engine block. Look for oil contamination in connectors, which indicates seal failure. Clean all connections with electrical contact cleaner and verify proper seating.

Step 2: Test Injector Resistance and Operation Using a digital multimeter, measure the resistance of the #2 cylinder injector (typically 0.5-1.5 ohms for this model). Disconnect the injector connector and check for voltage supply (should read battery voltage with key on). Perform a cylinder contribution test using diagnostic software compatible with Isuzu engines to isolate the problematic cylinder.

Step 3: Check Compression and Fuel Quality Conduct a compression test on cylinder #2 and compare readings to manufacturer specifications (typically 350-400 PSI). Readings below 300 PSI indicate internal engine wear. Inspect fuel quality and replace the fuel filter. For used machines, drain a fuel sample to check for water contamination or biological growth.

Step 4: Replace Faulty Components Based on diagnostic findings, replace the fuel injector, repair wiring, or address compression issues. After repairs, clear the fault code using a diagnostic scanner, perform a regeneration cycle if equipped with DPF, and conduct a test run under load.

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Disclaimer: This guide provides general diagnostic information for the Sumitomo SH80-6B. Always consult the manufacturer's service manual and consider professional assessment for complex engine repairs, especially on used equipment with unknown maintenance history.