DEF Tank Heater Circuit Malfunction
2009-2013 Audi A3 2.0L TDI
Description
The DEF tank and line heating system has a circuit fault. The heater prevents DEF from freezing (DEF freezes at 12F/-11C).
Symptoms
- DEF frozen in cold weather
- No DEF dosing in winter
- SCR system inoperative when cold
- Derate warning in cold conditions
- DEF warning light in winter
Common Causes
- Heater element failure
- Heater relay fault
- Wiring damage from road debris
- Fuse blown
- Control module heater driver failure
Diagnostic Steps
- Test DEF heater element resistance
- Check heater relay operation
- Inspect wiring to DEF tank heater
- Test coolant-based heater flow (if equipped)
- Verify heater activation below threshold temperature
Repair Notes
Replace DEF tank heater element or relay. Inspect wiring for road damage. Critical for cold-climate operation.
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
P3836 on Other Vehicles
Common Questions
What does code P3836 mean on a 2009-2013 Audi A3?
P3836 stands for "DEF Tank Heater Circuit Malfunction". The DEF tank and line heating system has a circuit fault. The heater prevents DEF from freezing (DEF freezes at 12F/-11C).
What are the symptoms of P3836 on a Audi A3?
Common symptoms of P3836 include: DEF frozen in cold weather, No DEF dosing in winter, SCR system inoperative when cold, Derate warning in cold conditions, DEF warning light in winter.
What causes P3836 on a 2009-2013 Audi A3?
Common causes of P3836 include: Heater element failure, Heater relay fault, Wiring damage from road debris, Fuse blown, Control module heater driver failure.