P20DD: Exhaust Aftertreatment Fuel Pressure Sensor Circuit
Standardized SAE J2012 code · P20xx — Fuel & air metering and auxiliary emission controls
What does P20DD mean?
The pressure sensor in the feed line of the exhaust doser lets the control unit meter fuel and spot a stuck valve or plugged nozzle. This code is the general circuit fault of that sensor; signal too low, too high and unsteady have their own codes (P20DF, P20E0, P20E1). Volvo and Mack store it as P20DD13 (open circuit) and issued bulletins for Mack TD with MP10 and Volvo VNL/VNX with the D16 engine, where an internally failed AHI harness sets it together with P249F00 and P113413; the harness is replaced. Guide KC-2157 points to the sensor's wiring and connector. With no valid pressure reading, dosing and regeneration are blocked.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light on
- Active regeneration blocked
- Further codes for the reference voltage or the dosing system
Common causes
- High Internally damaged harness to the dosing module and its sensor
- Medium Loose or corroded sensor connector
- Low Failed pressure sensor
Likelihood is a general estimate across vehicles; your make and model may differ.
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