DEF System Purge Valve Malfunction
2009-2013 Audi A3 2.0L TDI
Description
The DEF system purge valve that drains DEF lines back to the tank during shutdown (to prevent freezing) has malfunctioned.
Symptoms
- DEF lines freeze in cold weather
- DEF system inoperative after cold soak
- Check Engine Light in cold conditions
- DEF pressure does not build on startup
- SCR system delayed activation in winter
Common Causes
- Purge valve stuck open or closed
- Purge valve solenoid failure
- Wiring fault to purge valve
- Valve frozen in position
- Control circuit fault
Diagnostic Steps
- Test purge valve operation at shutdown
- Command valve via scan tool
- Check valve solenoid resistance
- Inspect valve for ice or crystallization
- Monitor DEF line pressure during purge cycle
Repair Notes
Replace DEF purge valve. Ensure DEF line heaters function to prevent future freeze damage.
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
P3839 on Other Vehicles
Common Questions
What does code P3839 mean on a 2009-2013 Audi A3?
P3839 stands for "DEF System Purge Valve Malfunction". The DEF system purge valve that drains DEF lines back to the tank during shutdown (to prevent freezing) has malfunctioned.
What are the symptoms of P3839 on a Audi A3?
Common symptoms of P3839 include: DEF lines freeze in cold weather, DEF system inoperative after cold soak, Check Engine Light in cold conditions, DEF pressure does not build on startup, SCR system delayed activation in winter.
What causes P3839 on a 2009-2013 Audi A3?
Common causes of P3839 include: Purge valve stuck open or closed, Purge valve solenoid failure, Wiring fault to purge valve, Valve frozen in position, Control circuit fault.