Reducing Agent Pressure Sensor Range/Performance Problem

The computer can't get a proper reading from the sensor that tells it how much pressure the fluid is under, which is important for controlling emissions.

The ECM expects a voltage signal from the pressure sensor within a specific range (typically 0.5V to 4.5V depending on the system). If it detects a voltage outside of this range consistently for a few seconds, it triggers this code.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Inspect the wiring and connectors to the reducing agent pressure sensor for damage or corrosion. Repair or replace as necessary. Decision: If damage is found, repair and retest. If no damage, move to step 2.
2. 22. Check the reducing agent pressure sensor with a multimeter. Measure the voltage signal during engine operation. Decision: If the voltage is within 0.5V to 4.5V, move to step 3. If it's out of range, replace the sensor and retest.
3. 33. Evaluate the condition of the diesel exhaust fluid (DEF). Ensure it meets manufacturer specifications and is not contaminated. Decision: If DEF is bad, replace it and retest. If DEF is good, check for restrictions in the DEF line or injector.

• Damaged wiring or connectors to the pressure sensor.
• Faulty pressure sensor itself.
• Clogged or restricted DEF line or injector.
• Defective diesel exhaust fluid (DEF).

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