ECU has detected a fault in one of the operating systems

When the ECU detects a problem with one of the operating systems, a trouble code is stored in its memory and the "Check Engine" or "Service Engine Soon" light will be illuminated.

Table of Contents

• 1. Symptoms
  • 1.1 Check Engine Light is On

Symptoms

Check Engine Light is On

The "Check Engine" or "Service Engine Soon" light are illuminated by the ECU. When a sensor registers a certain measurement, the ECU will store a code and illuminate the Check Engine light. The code can then be read by a technician to determine the cause of the fault.