DPF Regeneration Incomplete - Multiple Attempts
2009-2013 Audi A3 2.0L TDI
Description
The DPF has failed to complete a regeneration cycle after multiple attempts. Soot loading continues to increase.
Symptoms
- DPF warning light
- Reduced power
- Forced limp mode
- Excessive exhaust temperature warnings
- Strong exhaust smell during regen attempts
- Fuel dilution of engine oil
Common Causes
- Driving pattern prevents regen completion (short trips)
- EGR system fault preventing proper temperature
- Injector fault affecting post-injection for regen
- DPF catalyst coating degraded
- Exhaust temperature sensor error
Diagnostic Steps
- Check DPF soot loading level
- Review regen history and completion rates
- Test exhaust temperatures during regen attempt
- Check EGR system operation
- Inspect fuel injectors for proper post-injection
Repair Notes
Perform forced DPF regeneration with scan tool. If soot loading is critical, DPF cleaning service may be needed. Address root cause preventing regen completion.
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
P3851 on Other Vehicles
Common Questions
What does code P3851 mean on a 2009-2013 Audi A3?
P3851 stands for "DPF Regeneration Incomplete - Multiple Attempts". The DPF has failed to complete a regeneration cycle after multiple attempts. Soot loading continues to increase.
What are the symptoms of P3851 on a Audi A3?
Common symptoms of P3851 include: DPF warning light, Reduced power, Forced limp mode, Excessive exhaust temperature warnings, Strong exhaust smell during regen attempts, Fuel dilution of engine oil.
What causes P3851 on a 2009-2013 Audi A3?
Common causes of P3851 include: Driving pattern prevents regen completion (short trips), EGR system fault preventing proper temperature, Injector fault affecting post-injection for regen, DPF catalyst coating degraded, Exhaust temperature sensor error.