P3836moderate severityPowertrain
DEF Tank Heater Circuit Malfunction
on 2011 Audi A3 2.0L TDI I4 · FWD
What this code means
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.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1