Common Excavator Engine Fault Codes & Basic Troubleshooting Guide

April 17, 2026

For construction and earthmoving equipment owners and operators, unexpected excavator engine issues can lead to costly downtime, delayed projects, and unnecessary repair expenses. This guide covers universal excavator engine faults, including hard starting, overheating, and loss of power, with simple diagnostic steps suitable for beginners. The fault codes below apply to most mainstream excavator brands, helping you identify problems quickly and reduce equipment idle time.

Common Fault Codes & What They Mean

  • P0087 – Fuel Rail Pressure Too Low
  • P0088 – Fuel Rail Pressure Too High
  • P0201 – P0206 – Cylinder Injector Circuit Malfunction (1–6)
  • P0335 – Crankshaft Position Sensor Circuit Malfunction
  • P0340 – Camshaft Position Sensor Circuit Malfunction
  • P0118 – Engine Coolant Temperature Sensor Circuit High Input
  • P0522 – Engine Oil Pressure Sensor Circuit Low Voltage

Typical Engine Failure Symptoms

  1. Hard Starting or No Start
    Caused by abnormal fuel pressure, faulty crankshaft/camshaft sensors, or injector issues. The engine may crank excessively but fail to fire.
  2. Engine Overheating
    Triggered by coolant temperature sensor faults, insufficient coolant, or poor heat dissipation, leading to high-temperature warnings and power limitation.
  3. Loss of Power & Poor Performance
    Low oil pressure, unstable fuel rail pressure, or cylinder injector faults often result in weak acceleration, unstable idling, and inability to maintain working speed.

Basic Troubleshooting Steps for Beginners

1. Check Fuel System (For P0087 / P0088 / P0201–P0206)
Inspect fuel filters for clogging, ensure clean and sufficient diesel fuel, check fuel lines for leaks or air intake, and verify injector wiring connections.

2. Inspect Engine Sensors (For P0335 / P0340 / P0118)
Check sensor wiring for damage or looseness, clean sensor surfaces, and confirm correct installation position. Faulty sensors often cause starting and temperature errors.

3. Monitor Oil & Cooling System (For P0522 / P0118)
Check engine oil level and quality, inspect the oil pressure sensor connection, verify coolant level, and clean the radiator to avoid overheating.

4. Reset Fault Codes
After basic inspection, use a diagnostic tool to clear trouble codes. If codes reappear, further professional testing is recommended.

Why This Matters

Basic troubleshooting allows you to resolve simple issues without delay, avoiding prolonged downtime and reducing maintenance costs. Always prioritize safety during inspection: stop the engine, disconnect the power supply when necessary, and consult professional mechanics for complex internal failures.

With this universal fault code guide, both new and experienced operators can quickly diagnose common excavator engine problems, keep equipment running efficiently, and maintain project productivity.