Reductant Pressure Sensor Circuit Low
The Reductant Pressure Sensor is reporting low voltage readings.
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What it means (plain English)
The pressure sensor that measures the DEF fluid is detecting a pressure that's too low, which can indicate a problem with the sensor or the DEF system itself.
What the computer is actually seeing
The engine control module (ECM) sees the reductant pressure below the expected threshold, typically below 0.5 volts when it should be between 0.5 to 4.5 volts under normal operation.
What a healthy reading looks like
Reductant pressure should typically read between 0.5 to 4.5 volts from the sensor; below 0.5 volts indicates a fault.
Guided diagnostic — the DiagCoach way
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.
- 11. Check DEF fluid level in the tank; it should be above the minimum mark. If low, refill to spec and clear codes.
- 22. Inspect wiring and connector at the reductant pressure sensor for damage or corrosion. Repair as necessary. If okay, proceed.
- 33. Measure the voltage at the reductant pressure sensor connector with key on, engine off. It should be between 0.5 to 4.5 volts; if less than 0.5 volts, replace the sensor.
- 44. If voltage is correct, check for open circuits or shorts in the wiring between the sensor and ECM.
- 55. If wiring and sensor are both good, consider updating or reprogramming the ECM software.
Common causes
- Faulty reductant pressure sensor
- Wiring issue in the sensor circuit
- Low DEF fluid level
- Clogged DEF injector
- Faulty ECM software
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to repair soon, as it can affect emissions and may cause limp mode.
Will this code come back after clearing it?
If the underlying problem isn't fixed, it will likely return.
Why does this code pair with others like P204F?
These codes often relate to the same DEF system components or operations, indicating a systemic issue.
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