Reductant Injection Air Pressure Sensor A/B Correlation

Where it lives

For P209E, start at the sensor the description names.

Check these first

• Sensor A and sensor B readings that disagree under the same air pressure
• A failed reductant injection air pressure sensor A or B
• A restriction feeding only one sensor
• A wiring fault on one of the two sensor circuits

What to do next

1. Read both reductant injection air pressure sensors on a scan tool
2. Compare sensor A and sensor B under steady air pressure
3. Test the sensor A and sensor B circuits for faults
4. Check the air supply to each sensor for a restriction
5. Replace the sensor that reads off if the circuits test good
6. Clear the code and retest

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