SevereAffected: 2008-201570,000–140,000 miles

Audi A4 B8 2.0 TDI 143bhp — EGR Cooler Failure and Coolant Loss

EGR cooler failure is common on the B8 A4 TDI. Internal corrosion allows coolant to leak into the intake — initially causing rough running and white smoke.

Severity

Severe

DIY Difficulty

Hard

Est. Cost

£500–£900

OBD Codes

P0401P0128

Component Diagram

EGR

Typical layout and location for the EGR assembly.

Reference Illustration

Symptoms

Coolant level dropping
White smoke with sweet smell
Rough running
P0401 EGR code

Root Cause

Coolant passages inside the EGR cooler corrode. Coolant enters the recirculated exhaust path and flows into the intake manifold.

How To Fix

Pressure test cooling system
Replace EGR cooler and valve together
Flush intake manifold
OEM Audi/Pierburg part: £500-900 fitted

Estimated Repair Costs

Repair Option	Est. Cost (GBP)
DIY (parts only)	£200–£360
Independent Garage	£500–£900
Main Dealership	£800–£1440

Other Faults on This Variant

Timing Belt Failure

Critical

2008-2015100,000–140,000 miles£400–£700

The B8 A4 2.0 TDI uses a timing belt with a 140,000-mile service interval. Many specialists recommend 100,000 miles. Belt failure is catastrophic on this interference engine.

DPF Blockage

Moderate

2008-201540,000–90,000 miles£200–£1400

The A4 B8 TDI is frequently used as a company car on short local journeys rather than motorway runs. DPF blockage is the most common ownership complaint.

Turbocharger Failure

Severe

2008-2015100,000–180,000 miles£650–£1100

Turbocharger failure on the B8 A4 TDI mirrors the wider VAG TDI pattern — oil sludge in the feed pipe causes bearing failure, often presenting as a sudden loss of boost.

Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.