What is Doosan DX215-9C Fault Code E000175-03 (P0198)?

Fault Code E000175-03 (P0198) indicates an Engine Oil Temperature (EOT) Sensor Circuit High Voltage condition in your Doosan DX215-9C excavator. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally high voltage signal from the engine oil temperature sensor, typically above 4.5-4.8 volts, which is outside the normal operating range.

The engine oil temperature sensor plays a critical role in the Common Rail diesel engine management system found in the DX215-9C. It monitors oil temperature to optimize fuel injection timing, control regeneration cycles for the Diesel Particulate Filter (DPF), and protect the engine from thermal damage. When this sensor circuit fails high, the ECM cannot accurately determine oil temperature, potentially leading to improper engine protection strategies and reduced performance.

Common Symptoms

• Check Engine Light or Malfunction Indicator Lamp (MIL) illuminated on the instrument cluster
• Engine derate mode activated, limiting maximum RPM to approximately 1,800-2,000 RPM to protect the engine
• DPF regeneration issues, with incomplete or failed regeneration cycles causing exhaust backpressure
• Inaccurate oil temperature readings displayed on the monitor (often showing extremely low or no temperature)
• Reduced hydraulic performance during cold starts due to improper warm-up fuel mapping

Potential Causes

The most common technical causes for this high voltage condition on used Doosan excavators include:

• Open circuit in the sensor wiring harness, particularly at known rub points near the engine mount brackets or along the valve cover
• Failed engine oil temperature sensor with internal open circuit (common failure mode after 5,000+ operating hours)
• Corroded or damaged connector pins at the sensor or ECM connection points due to moisture intrusion
• Broken or frayed wiring in the harness between the sensor and ECM, especially where the harness passes through bulkhead grommets
• ECM internal fault (rare, but possible in high-hour machines with previous electrical issues)

How to Troubleshoot and Fix Code E000175-03 (P0198)

Step 1: Visual Inspection Begin with a thorough visual inspection of the engine oil temperature sensor located on the engine block near the oil filter housing. Check the sensor connector for corrosion, bent pins, moisture, or oil contamination. On used excavators, inspect the entire wiring harness from sensor to ECM for chafing, particularly where it contacts frame members or passes through grommets.

Step 2: Electrical Testing Disconnect the sensor and use a digital multimeter to measure resistance across the sensor terminals. A functioning sensor should show approximately 2,500-3,000 ohms at room temperature (68°F/20°C). An open circuit (infinite resistance) confirms sensor failure. Next, check the harness continuity from the sensor connector to the ECM connector—both signal and ground circuits should show less than 5 ohms resistance.

Step 3: Voltage Check With the ignition on and sensor disconnected, measure voltage at the harness connector. You should see approximately 5 volts reference voltage from the ECM. If voltage is absent, trace the circuit back toward the ECM for breaks. If voltage is present, the issue is likely the sensor itself.

Step 4: Address Root Cause For used excavators, don't simply replace the sensor without addressing underlying issues. Check for harness wear patterns, secure loose wiring with proper routing clips, and apply dielectric grease to all connector pins before reassembly. If replacing the sensor, use genuine Doosan parts (part number may vary—consult your parts manual) to ensure proper resistance curve matching for accurate ECM calibration.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Doosan service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues or if you lack proper diagnostic equipment.