Doosan DX220LC-9C Fault Code E000157-31: Complete Diagnostic Guide

What is Doosan DX220LC-9C Fault Code E000157-31?

Fault Code E000157-31 indicates a hydraulic pump pressure sensor circuit malfunction, specifically a voltage signal that is out of normal operating range on the main hydraulic system. This code is triggered when the Electronic Control Module (ECM) detects abnormal voltage readings from the main pump pressure sensor, which monitors hydraulic system pressure to optimize fuel efficiency and machine performance.

This code is critical for the DX220LC-9C because the hydraulic pressure sensor directly influences the engine-pump matching control system. When this sensor fails or sends incorrect signals, the ECM cannot properly regulate pump displacement, leading to reduced performance, excessive fuel consumption, and potential damage to hydraulic components. On used excavators, this fault often indicates sensor degradation or wiring issues common in machines with 5,000+ operating hours.

Common Symptoms

• Reduced hydraulic power during digging or lifting operations, with noticeably slower cycle times
• Intermittent or constant warning light on the instrument cluster, often accompanied by code display on the monitor panel
• Erratic engine RPM fluctuations when operating under load, as the ECM struggles to match engine output to hydraulic demand
• Increased fuel consumption due to improper engine-pump coordination
• Delayed response in hydraulic functions, particularly during combined operations (swing and boom movement simultaneously)

Potential Causes

Sensor-Related Issues:

• Failed or degraded main pump pressure sensor (common failure point after 6,000+ hours)
• Internal sensor contamination from hydraulic fluid breakdown or metal particles

Electrical/Wiring Problems:

• Damaged or corroded sensor harness connector at the hydraulic pump mounting location
• Wiring harness chafing or rubbing against pump housing or nearby components (known issue on DX220LC models near the pump mounting bracket)
• Broken or frayed wires in the sensor circuit due to vibration fatigue

System Issues:

• Low voltage supply from ECM to the sensor (should be 5V reference)
• ECM internal fault affecting sensor circuit processing (rare but possible on high-hour machines)
• Contaminated hydraulic oil causing sensor membrane failure

How to Troubleshoot and Fix Code E000157-31

Step 1: Visual Inspection and Connector Check Begin by locating the main pump pressure sensor on the hydraulic pump assembly (typically mounted on the pump body near the control valve). Inspect the sensor connector for corrosion, bent pins, or hydraulic oil contamination—a common issue on used excavators. Disconnect the connector and examine both male and female terminals. Clean with electrical contact cleaner and check for moisture. On used machines, pay special attention to the harness routing from the sensor to the main wiring loom, looking for signs of rubbing against the pump housing or frame.

Step 2: Electrical Testing with Multimeter With the ignition OFF, disconnect the sensor and measure resistance across the sensor terminals. Typical resistance should be between 50-150 ohms (consult Doosan service manual for exact specifications). Next, check the harness side for continuity to the ECM and measure the 5V reference voltage from the ECM with ignition ON. Use a digital multimeter capable of measuring voltage to 0.01V accuracy. If reference voltage is outside 4.8-5.2V range, suspect ECM issues or harness short circuits. Check for ground integrity at the sensor mounting point, as corrosion can cause intermittent faults.

Step 3: Sensor Replacement and System Verification If electrical tests indicate sensor failure, replace with a genuine Doosan pressure sensor (avoid aftermarket sensors on critical hydraulic monitoring systems). Before installation, inspect the sensor mounting port for metal debris or contamination, and ensure the O-ring seal is properly seated. After replacement, clear the fault code using Doosan EPOS diagnostic software or compatible scan tool. Perform a hydraulic system test under load to verify proper pressure readings (normal operating pressure: 320-350 bar). For used excavators, consider replacing the hydraulic oil filter simultaneously, as contaminated oil may have contributed to sensor failure.

---

Disclaimer: This guide provides general diagnostic information for Code E000157-31. Always consult the official Doosan service manual for your specific serial number and consult with a certified Doosan technician for complex repairs. Improper diagnosis can lead to additional component damage or safety hazards.