What is Kobelco SK460-8 Fault Code P0335?

Fault Code P0335 indicates a Crankshaft Position Sensor "A" Circuit malfunction. This diagnostic trouble code (DTC) means the Engine Control Module (ECM) has detected an irregular, missing, or intermittent signal from the crankshaft position sensor (CKP sensor).

On the Kobelco SK460-8, this sensor is critical for monitoring engine speed and crankshaft rotation position. The ECM uses this data to control fuel injection timing, ignition timing, and overall engine synchronization. When the signal fails or becomes erratic, the excavator's Isuzu engine cannot operate efficiently or may fail to start altogether. This code directly impacts engine performance, making it a high-priority issue for operators and mechanics working with used heavy equipment.

Common Symptoms

When P0335 is active on your SK460-8, you may experience:

• Engine cranks but fails to start or has extremely difficult starting conditions
• Check Engine Light (CEL) or malfunction indicator lamp illuminated on the dashboard
• Rough idling, stalling, or sudden engine shutdown during operation
• Loss of power or hesitation during hydraulic operations due to inconsistent engine RPM
• No tachometer reading or erratic RPM display on the instrument cluster

Potential Causes

Several factors can trigger P0335 on used Kobelco excavators:

• Failed or worn crankshaft position sensor due to heat exposure, vibration, or age-related deterioration
• Damaged or corroded wiring harness and connectors leading to the CKP sensor—common in older machines exposed to moisture and debris
• Broken or missing reluctor ring teeth on the crankshaft (rare but possible in high-hour machines)
• Poor electrical ground connections or corroded ground straps affecting sensor signal quality
• ECM software issues or internal ECM failure (less common)
• Incorrect sensor air gap if the sensor was previously replaced or disturbed during engine work

How to Troubleshoot and Fix Code P0335

Step 1: Visual Inspection
Locate the crankshaft position sensor on the engine block near the crankshaft pulley or flywheel housing. Inspect the sensor, wiring harness, and connector for physical damage, oil contamination, corrosion, or loose connections. On used excavators, check for harness wear at rub points near engine mounts.

Step 2: Test Sensor Resistance
Disconnect the CKP sensor connector. Using a digital multimeter, measure the sensor's resistance between the two sensor terminals. Typical readings range from 200-900 ohms (consult your Kobelco service manual for exact specifications). Readings outside this range indicate sensor failure.

Step 3: Check Signal Voltage
Reconnect the sensor and back-probe the connector wires with your multimeter set to AC voltage. Crank the engine and observe for an AC voltage signal (typically 0.3-1.0V AC fluctuating). No signal or flat readings confirm sensor or reluctor ring issues.

Step 4: Inspect Reluctor Ring and Air Gap
Remove the sensor and visually inspect the reluctor ring (toothed wheel) on the crankshaft for damaged or missing teeth. Verify the air gap between sensor tip and reluctor ring is within specification (usually 0.5-1.5mm). Adjust or replace as needed.

Step 5: Clear Code and Test
After repairs, clear the fault code using Kobelco diagnostic software or a compatible scan tool. Test-run the machine under load to confirm the fix.

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Disclaimer: This guide provides general troubleshooting steps. Always consult the official Kobelco service manual and consider professional diagnostic assistance for complex electrical issues on used excavators.