P0409 - Exhaust Gas Recirculation Sensor B Circuit

The ECM detected a fault in the EGR sensor B circuit.

Code Overview

The ECM detected a fault in the EGR sensor B circuit.

Common Causes

• Failed EGR sensor
• Damaged wiring or connector
• Control circuit issue

Diagnostic Steps

1. Inspect the EGR sensor connector and harness
2. Check command and feedback data if supported
3. Inspect the EGR valve and passages for buildup

Likely Repairs & Cost Guides

Use test results to confirm the fault before pricing the repair.

Related OBD Codes

Browse the closest code-family pages when the same fault pattern often shows up nearby.

Next Steps

Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.