P1001 – Manufacturer-Specific Diagnostic Mode Active

Description

The ECM indicates a manufacturer-specific diagnostic mode or incomplete readiness.

Want to confirm the real cause of this fault code?

A high-quality OBD2 scanner gives you live data, fuel trims, sensor readings and freeze-frame information — exactly what you need to verify the root cause of this code with confidence.

View Recommended Scanners

Symptoms

  • Hard starting

Causes

  • Diagnostic mode active
  • Recent ECU reset

Diagnosis

  • Complete drive cycle
  • Verify readiness

Repair

  • No repair needed

Related Problems