What is Kobelco SK135SRLC-2 Fault Code A245?

Fault Code A245 on the Kobelco SK135SRLC-2 indicates a malfunction in the hydraulic oil temperature sensor circuit. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an abnormal signal from the hydraulic oil temperature sensor, typically indicating an open circuit, short circuit, or sensor reading outside the acceptable voltage range (usually 0.5-4.5V).

This code is critical for the SK135SRLC-2 because hydraulic oil temperature directly affects system viscosity, component wear, and operational safety. The ECM uses this sensor data to regulate engine performance, prevent overheating damage to hydraulic components, and protect seals from thermal degradation. When this sensor fails, the machine may enter a protective derate mode or display inaccurate temperature readings, potentially leading to catastrophic hydraulic system failure if overheating goes undetected.

Common Symptoms

• Hydraulic oil temperature warning light illuminated on the instrument cluster, even when oil feels cool to touch
• Reduced engine power or automatic engine speed limitation as the ECM assumes worst-case temperature scenario
• Erratic temperature gauge readings that fluctuate wildly or remain pegged at minimum/maximum
• Sluggish hydraulic response during cold starts if ECM cannot properly manage warm-up cycle
• Stored fault code A245 visible when using Kobelco diagnostic software or compatible scan tool

Potential Causes

• Damaged or corroded wiring harness connections at the sensor plug (common wear point near hydraulic tank on used machines)
• Failed hydraulic oil temperature sensor due to internal thermistor breakdown or moisture contamination
• Chafed wiring along the main harness routing path between hydraulic tank and cab floor where vibration causes insulation wear
• Corroded pins in the ECM connector or sensor connector due to water intrusion from damaged cab floor seals
• ECM internal circuit failure (rare, but possible in high-hour used excavators with electrical history)
• Poor ground connection at chassis ground points near hydraulic reservoir

How to Troubleshoot and Fix Code A245

Step 1: Visual Inspection Begin by inspecting the hydraulic oil temperature sensor located on or near the hydraulic reservoir. Check for physical damage, corroded connector pins, or oil contamination in the electrical connector. On used SK135SRLC-2 excavators, examine the wiring harness routing from sensor to cab for chafe marks, especially where it passes near moving components or sharp edges.

Step 2: Sensor Resistance Testing Disconnect the sensor connector and measure resistance across the sensor terminals using a digital multimeter. At room temperature (20°C/68°F), resistance should typically read 2,000-3,000 ohms (consult Kobelco service manual for exact specifications). Compare readings at different temperatures if possible; resistance should decrease as temperature increases, following a predictable curve.

Step 3: Circuit Voltage Testing With ignition ON and sensor disconnected, check for 5-volt reference voltage at the harness connector from the ECM. Test signal wire continuity back to the ECM and verify ground circuit integrity (should read less than 1 ohm resistance to chassis ground). Any open circuits or voltage deviations indicate wiring damage.

Step 4: Connector and Harness Repair For used excavators, cleaning corroded connectors with electrical contact cleaner and applying dielectric grease often resolves intermittent codes. Replace any sections of harness showing insulation damage, ensuring proper routing away from heat sources and moving parts. Check that all harness securing clips are intact to prevent future chafing.

Step 5: Component Replacement If sensor tests reveal out-of-spec readings, replace the hydraulic oil temperature sensor with a genuine Kobelco part. Clear the fault code using diagnostic software and operate the machine through a complete heat cycle to verify the repair.

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Disclaimer: This guide provides general troubleshooting procedures for informational purposes. Always consult the official Kobelco service manual for your specific machine serial number and seek assistance from certified heavy equipment technicians for complex electrical diagnostics or if you're unfamiliar with high-voltage systems.