EGR Sensor B Circuit High

Where it lives

For P0408, the circuit described runs through the sensor. The description of P0408 reports a fault at the sensor.

Check these first

• A failed EGR valve position sensor B
• An open in the sensor B signal wire
• A sensor B connector with a poor pin fit
• A carbon bound EGR valve holding the sensor high
• An ECM reference fault on the sensor B circuit

What to do next

1. Read the sensor B voltage key on and running
2. Check the sensor B signal wire for an open
3. Wiggle the sensor B connector while watching the voltage
4. Clean carbon from the EGR valve and passages
5. Replace sensor B if the voltage stays high
6. Clear the code and retest

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