What is Kobelco SK135SR-2 Fault Code P0336?

Fault Code P0336 on the Kobelco SK135SR-2 indicates a Crankshaft Position Sensor "A" Circuit Range/Performance Problem. This diagnostic trouble code (DTC) means the Engine Control Module (ECM) has detected an irregular or inconsistent signal from the crankshaft position sensor (CKP sensor), which monitors the rotational speed and exact position of the crankshaft.

The crankshaft position sensor is critical for engine timing operations on this excavator. It provides real-time data to the ECM to control fuel injection timing, ignition timing (on certain engine types), and overall engine synchronization. When the sensor signal falls outside the expected range or shows erratic performance patterns, the ECM triggers P0336. On used Kobelco SK135SR-2 machines, this can severely impact engine performance, fuel efficiency, and starting reliability, making immediate diagnosis essential.

Common Symptoms

• Rough or erratic engine idle with noticeable vibrations or inconsistent RPM
• Hard starting conditions or extended cranking time before the engine fires
• Engine stalling during operation, particularly under load or at idle
• Loss of power or hesitation during acceleration and hydraulic work cycles
• Check Engine Light (CEL) illuminated on the instrument cluster

Potential Causes

The most common technical causes for P0336 on used SK135SR-2 excavators include:

• Worn or damaged crankshaft position sensor due to heat exposure, vibration, or age-related degradation
• Corroded or loose electrical connectors at the sensor harness connection point
• Damaged sensor wiring harness caused by rubbing against engine components, heat shields, or mounting brackets (common wear point near the bell housing area)
• Contaminated sensor face from oil leaks, metal debris, or dirt buildup blocking the magnetic pickup
• Damaged reluctor ring (tone wheel) on the crankshaft with missing or damaged teeth
• Weak battery or charging system issues causing voltage fluctuations that affect sensor signal quality
• ECM software issues or internal ECM faults (less common)

How to Troubleshoot and Fix Code P0336

Step 1: Visual Inspection Begin by locating the crankshaft position sensor (typically mounted near the flywheel/flexplate area or front crankshaft pulley). Inspect the sensor body for physical damage, oil contamination, or cracks. Check the wiring harness for signs of chafing, burns, or damage—especially at rub points near engine mounts and heat sources common in used machines.

Step 2: Connector and Wiring Check Disconnect the CKP sensor connector and thoroughly inspect for corrosion, bent pins, or moisture intrusion. Clean contacts with electrical contact cleaner if needed. Using a digital multimeter, check sensor resistance (typically 200-1000 ohms, consult service manual for exact specifications). Test wiring continuity from sensor connector back to the ECM connector.

Step 3: Sensor Gap and Reluctor Ring Inspection Verify the air gap between the sensor tip and the reluctor ring meets manufacturer specifications (usually 0.5-1.5mm). Inspect the reluctor ring for missing teeth, cracks, or metal debris accumulation. On used excavators, metal shavings from engine wear can accumulate here.

Step 4: Voltage Signal Testing With the sensor connected, use an oscilloscope or advanced multimeter to monitor the AC voltage signal while cranking the engine. The signal should show consistent waveform peaks. Erratic or absent signals indicate sensor or reluctor ring failure.

Step 5: Replace or Repair If testing confirms sensor failure, replace the crankshaft position sensor with an OEM or high-quality aftermarket unit. If wiring damage is found, repair harness sections and ensure proper routing away from heat and friction points. Clear codes using Kobelco diagnostic software or compatible scan tool and test operation.

Disclaimer: This guide provides general diagnostic information. For used excavators with complex electrical issues or persistent codes, consult a certified Kobelco technician or heavy equipment diesel specialist with access to manufacturer-specific diagnostic tools and wiring diagrams.