What is Doosan Excavator Fault Code E000168-02?

Fault Code E000168-02 indicates a hydraulic oil temperature sensor circuit malfunction with an intermittent or erratic signal in Doosan excavators. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects abnormal voltage readings or inconsistent data from the hydraulic oil temperature sensor, specifically indicating a signal that falls outside the expected range or fluctuates unpredictably.

This code is critical for Doosan excavators because the hydraulic oil temperature sensor plays a vital role in protecting the hydraulic system from overheating and maintaining optimal operating efficiency. When the ECM cannot reliably monitor hydraulic oil temperature, it may default to protective modes that limit machine performance, potentially causing unexpected power reductions or complete hydraulic function restrictions. For used excavators, this sensor circuit is particularly vulnerable to age-related degradation, making early diagnosis essential to prevent costly hydraulic system damage.

Common Symptoms

• Intermittent warning light or alarm on the instrument panel indicating hydraulic system issues
• Erratic hydraulic performance with inconsistent response times or reduced power during operation
• Machine derate mode where excavator automatically limits engine RPM or hydraulic flow to protect components
• Temperature gauge fluctuations showing unrealistic readings (sudden spikes or drops) on the display
• ECM logging multiple instances of the fault code, even when hydraulic oil temperature appears normal during physical inspection

Potential Causes

The most common technical causes for Code E000168-02 in Doosan excavators include:

• Damaged or corroded sensor connector at the hydraulic oil tank, especially common in used machines exposed to moisture and debris
• Frayed wiring harness near moving components or routing points where cables rub against the chassis or boom structure
• Failed hydraulic oil temperature sensor due to internal resistance drift or element degradation from thermal cycling
• Loose or oxidized ground connection affecting the sensor circuit reference voltage
• ECM software glitches or outdated firmware requiring calibration updates
• Contaminated hydraulic oil causing sensor element fouling (less common but possible in poorly maintained used equipment)

How to Troubleshoot and Fix Code E000168-02

Step 1: Visual Inspection and Connection Check Begin by locating the hydraulic oil temperature sensor (typically mounted on or near the hydraulic reservoir). Inspect the sensor connector for corrosion, bent pins, moisture intrusion, or loose connections. On used excavators, pay special attention to connector seal integrity. Clean contacts with electrical contact cleaner and ensure the connector locks securely.

Step 2: Wiring Harness Examination Trace the sensor wiring harness from the sensor back to the ECM, checking for wear points, particularly where cables pass through bulkheads or near moving hydraulic lines. Look for abraded insulation, exposed copper, or signs of previous repairs. Use a digital multimeter to check for continuity between the sensor connector and ECM pins (consult Doosan wiring diagrams for specific pin locations).

Step 3: Sensor Circuit Testing With the sensor disconnected and ignition on, measure the reference voltage at the sensor connector (typically 5 volts). Then measure the sensor resistance across its terminals using an ohmmeter—compare readings against Doosan specifications (usually 200-400 ohms at room temperature, varying with temperature). An out-of-spec reading indicates sensor replacement is necessary.

Step 4: Dynamic Testing and Software Diagnostics Reconnect the sensor and use Doosan diagnostic software (DMS or G-SCAN) to monitor live data while the machine operates. Watch for voltage spikes, dropouts, or erratic signal patterns that confirm intermittent failure. Clear the code and perform a function test. If the code returns immediately, suspect ECM issues or internal wiring problems.

Step 5: Ground Circuit Verification Check the ground circuit integrity by measuring resistance from the sensor ground pin to chassis ground (should be less than 1 ohm). Poor grounds are extremely common in used excavators due to corrosion at mounting points.

For used excavators specifically: Before replacing the sensor, thoroughly inspect for harness chafing at known wear points and test all connections under vibration (gently wiggle connectors while monitoring live data). Many intermittent codes are resolved by addressing connector corrosion rather than parts replacement.

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Disclaimer: This guide provides general troubleshooting information for Doosan fault code E000168-02. Always consult the manufacturer's service manual for your specific model and serial number. If you lack proper diagnostic tools or experience with electrical systems, consult a certified Doosan technician to avoid misdiagnosis or safety hazards.