Reductant Injection Air Pressure Sensor B Circuit Low

Where it lives

For P209C, the circuit described runs through the sensor. The description of P209C reports a fault at the sensor.

Check these first

• Low reductant injection air pressure feeding sensor B
• A restricted or blocked reductant injection air supply
• A short to ground on the sensor B signal wire
• A failed reductant injection air pressure sensor B

What to do next

1. Read reductant injection air pressure sensor B on a scan tool
2. Compare the sensor B reading to the commanded air pressure
3. Check the reductant injection air supply for a restriction
4. Test the sensor B signal wire for a short to ground
5. Replace the reductant injection air pressure sensor B if the circuit tests good
6. Clear the code and retest

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