P3871critical severityPowertrain
EGR Cooler Efficiency Below Threshold
on 2010 Audi A3 2.0L TDI I4 · FWD
What this code means
The EGR cooler is not reducing exhaust gas temperature sufficiently. This can indicate an internal leak or coolant passage blockage.
Symptoms
- Check Engine Light
- Elevated intake manifold temperature
- Increased NOx emissions
- Coolant level dropping slowly
- White smoke from exhaust (coolant)
- Sweet smell from exhaust
Common causes
- EGR cooler internal leak
- EGR cooler coolant passage blocked
- EGR cooler fins clogged with soot
- Thermostat affecting coolant temperature
- Insufficient coolant flow through cooler
Diagnostic steps
- Compare EGR cooler inlet and outlet temperatures
- Check coolant level and condition
- Pressure test EGR cooler
- Inspect exhaust for coolant contamination
- Monitor coolant consumption
Repair notes
Replace EGR cooler if leaking or if efficiency cannot be restored. An internal leak can cause catastrophic engine damage from hydro-lock.
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