XCMG XSX15 Fault Code 157-1: Complete Diagnostic Guide

What is XCMG XSX15 Fault Code 157-1?

Fault Code 157-1 indicates an abnormal voltage signal from the fuel injection pressure sensor circuit, specifically detecting a voltage reading that is higher than the manufacturer's specified range. This code is triggered when the Engine Control Module (ECM) receives a signal from the fuel rail pressure sensor that exceeds the normal operating parameters, typically above 4.5-5.0 volts.

This fault is critical for the XSX15 mini excavator because the fuel injection system relies on precise pressure monitoring to optimize combustion efficiency, engine power output, and emissions control. When the ECM cannot accurately read fuel pressure, it may force the engine into derate mode to prevent potential damage to the high-pressure fuel pump and injectors.

Common Symptoms

When fault code 157-1 is active on your XCMG XSX15, you may experience:

• Check Engine Light or malfunction indicator lamp illuminated on the dashboard
• Reduced engine power or automatic derate limiting RPM to 1500-2000 range
• Hard starting conditions, especially during cold starts
• Rough idle or inconsistent engine performance under load
• Black smoke from the exhaust due to improper fuel metering

Potential Causes

The most common technical causes for code 157-1 on used XCMG excavators include:

• Damaged or corroded wiring harness between the fuel pressure sensor and ECM (especially at connector pins)
• Failed fuel rail pressure sensor with internal short circuit or component degradation
• Chafed sensor wiring rubbing against the engine block or fuel lines near the injection pump
• Corroded electrical connectors due to moisture intrusion in the engine bay
• ECM internal fault (less common, but possible in high-hour machines)
• Poor ground connection at the sensor mounting point or harness ground terminal

How to Troubleshoot and Fix Code 157-1

Step 1: Visual Inspection Begin by inspecting the fuel pressure sensor located on the fuel rail near the injection pump. Check for physical damage, oil contamination on the connector, or visible corrosion. On used excavators, carefully examine the wiring harness for rub-through points where it contacts metal surfaces or vibrates against brackets.

Step 2: Electrical Testing Using a digital multimeter, disconnect the fuel pressure sensor connector and measure resistance across the sensor terminals. Typical readings should be 150-300 ohms (consult your service manual). Next, check for supply voltage at the connector—you should see approximately 5 volts from the ECM with the key on, engine off.

Step 3: Signal Wire Verification Inspect the signal wire (typically green or yellow) from sensor to ECM for continuity and shorts to ground. Check for voltage leakage by measuring between the signal wire and chassis ground—any reading above 0.2 volts indicates a short circuit or damaged insulation.

Step 4: Sensor Replacement and Calibration If testing reveals sensor failure, replace with an OEM-equivalent fuel pressure sensor and ensure proper torque specifications (typically 8-12 Nm). After installation, clear codes using XCMG diagnostic software or a compatible scan tool and perform a test cycle.

Important for Used Equipment: Before replacing expensive components, thoroughly clean all electrical connectors with contact cleaner and apply dielectric grease to prevent future corrosion—this resolves the issue in approximately 40% of used excavator cases.

---

Disclaimer: This guide provides general diagnostic information. Always consult your XCMG service manual and consider professional assistance for complex electrical diagnostics or if you lack proper testing equipment.