SCR System Efficiency Below Threshold
2009-2013 Audi A3 2.0L TDI
Description
The selective catalytic reduction system is not converting NOx emissions efficiently. The downstream NOx sensor shows higher than acceptable NOx levels.
Symptoms
- Check Engine Light
- DEF warning light
- Possible speed limitation countdown
- Increased NOx emissions
- Failed emissions test
- Derate mode if not addressed
Common Causes
- Degraded SCR catalyst
- Incorrect DEF quality
- DEF dosing system malfunction
- Exhaust temperature too low for SCR
- SCR catalyst contaminated by sulfur
Diagnostic Steps
- Read downstream NOx sensor values
- Check DEF quality with refractometer
- Monitor SCR inlet and outlet temperature
- Test DEF dosing quantity
- Inspect SCR catalyst for contamination
Repair Notes
Replace SCR catalyst if efficiency is permanently reduced. Verify DEF quality and dosing system. Check for fuel sulfur contamination.
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
P3830 on Other Vehicles
Common Questions
What does code P3830 mean on a 2009-2013 Audi A3?
P3830 stands for "SCR System Efficiency Below Threshold". The selective catalytic reduction system is not converting NOx emissions efficiently. The downstream NOx sensor shows higher than acceptable NOx levels.
What are the symptoms of P3830 on a Audi A3?
Common symptoms of P3830 include: Check Engine Light, DEF warning light, Possible speed limitation countdown, Increased NOx emissions, Failed emissions test, Derate mode if not addressed.
What causes P3830 on a 2009-2013 Audi A3?
Common causes of P3830 include: Degraded SCR catalyst, Incorrect DEF quality, DEF dosing system malfunction, Exhaust temperature too low for SCR, SCR catalyst contaminated by sulfur.