What is Kobelco SK140LC-8 Fault Code P0336?

Fault Code P0336 indicates a Crankshaft Position Sensor "A" Circuit Range/Performance problem. This code triggers when the Engine Control Module (ECM) detects an irregular or erratic signal from the crankshaft position sensor (CKP), which monitors the rotational speed and position of the crankshaft in real-time.

In the Kobelco SK140LC-8's Isuzu diesel engine, the CKP sensor is critical for proper fuel injection timing and ignition synchronization. When this sensor provides inconsistent data or loses signal intermittently, the ECM cannot accurately calculate engine timing, resulting in performance degradation or complete shutdown to protect engine components. This is especially problematic in used excavators where sensor wear and harness deterioration are common.

Common Symptoms

• Check Engine Light or malfunction indicator lamp illuminated on the instrument panel
• Rough idle or noticeable engine vibration during startup and low-speed operation
• Hard starting or extended cranking time, especially during cold starts
• Power loss or hesitation during heavy lifting operations or when raising engine RPM
• Engine stalling unexpectedly, particularly when returning to idle after high-load cycles

Potential Causes

The P0336 code on used SK140LC-8 excavators typically results from several age-related failures:

• Worn or contaminated CKP sensor face due to metal debris accumulation or oil contamination
• Damaged sensor wiring harness from rubbing against the engine block or flywheel housing (common wear point near the transmission bellhousing)
• Corroded or loose electrical connectors at the sensor or ECM, especially on machines with over 5,000 operating hours
• Damaged reluctor ring (tone wheel) on the crankshaft or flywheel with missing/damaged teeth
• Air gap issues between the CKP sensor tip and reluctor ring caused by improper installation or mounting bracket wear
• ECM internal faults though less common, can occur in high-hour machines

How to Troubleshoot and Fix Code P0336

Step 1: Visual Inspection Begin by inspecting the CKP sensor location (typically mounted near the flywheel housing on the engine's lower left side). Check for physical damage, excessive oil contamination, or metal debris buildup on the sensor face. Inspect the wiring harness for fraying, especially where it routes along the engine block—this is a known wear point on SK140LC-8 models.

Step 2: Electrical Testing Using a digital multimeter, disconnect the CKP sensor connector and measure resistance across the sensor terminals (typically 200-1,000 ohms for most Isuzu sensors—verify with service manual). Check for short circuits to ground and verify continuity through the entire harness back to the ECM. Inspect all connectors for corrosion or bent pins, common in used excavators operating in wet conditions.

Step 3: Air Gap and Reluctor Inspection Remove the CKP sensor and verify the air gap specification (usually 0.5-1.2mm). Use a feeler gauge to check clearance. Rotate the engine manually with a bar and inspect the reluctor ring through the sensor mounting hole for damaged, missing, or worn teeth. On used machines, accumulated rust or debris can alter the air gap.

Step 4: Signal Testing Reconnect the sensor and use a Kobelco diagnostic tool or compatible scan tool to monitor the CKP sensor signal pattern in real-time while cranking. An erratic waveform or missing pulses confirms sensor or reluctor failure. Compare voltage output (typically 0.5-5V AC) against factory specifications.

Step 5: Component Replacement If testing confirms sensor failure, replace with a genuine Kobelco/Isuzu part to ensure proper specifications. For used excavators with harness damage, replace the entire affected section rather than splicing—temporary repairs often fail under engine vibration and heat cycles.

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Disclaimer: This guide provides general troubleshooting information. Always consult the Kobelco SK140LC-8 service manual for exact specifications and torque values. If unfamiliar with diesel engine electrical systems, consult a certified Kobelco technician to prevent further damage or safety hazards.