P3831
DEF (Diesel Exhaust Fluid) Quality Sensor Malfunction
2009-2013 Audi A3 2.0L TDI
Moderate SeverityPowertrainGeneric (SAE)
Description
The DEF quality sensor that measures urea concentration in the DEF tank is malfunctioning.
Symptoms
- DEF quality warning
- Potential derate countdown
- Check Engine Light
- Unable to verify DEF concentration
- Service DEF system message
Common Causes
- DEF quality sensor failure
- Sensor contaminated by crystallized DEF
- Sensor wiring fault
- Sensor connector corrosion
- Diluted or incorrect DEF affecting sensor
Diagnostic Steps
- Read DEF quality sensor PID
- Test sensor with known-good DEF
- Inspect sensor for crystallization
- Check sensor wiring and connector
- Compare sensor reading to refractometer test
Repair Notes
Replace DEF quality sensor. Clean sensor mounting area of crystallized DEF. Use only API-certified DEF.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P3831 on Other Vehicles
Common Questions
What does code P3831 mean on a 2009-2013 Audi A3?
P3831 stands for "DEF (Diesel Exhaust Fluid) Quality Sensor Malfunction". The DEF quality sensor that measures urea concentration in the DEF tank is malfunctioning.
What are the symptoms of P3831 on a Audi A3?
Common symptoms of P3831 include: DEF quality warning, Potential derate countdown, Check Engine Light, Unable to verify DEF concentration, Service DEF system message.
What causes P3831 on a 2009-2013 Audi A3?
Common causes of P3831 include: DEF quality sensor failure, Sensor contaminated by crystallized DEF, Sensor wiring fault, Sensor connector corrosion, Diluted or incorrect DEF affecting sensor.