SevereAffected: 2012-202070,000–120,000 miles

Audi A3 8V 2.0 TDI 150bhp — Alternator / Smart Charge System Failure

Modern vehicles use smart charging systems to reduce engine load, but the complex regulators on the alternators frequently fail.

Severity

Severe

DIY Difficulty

Moderate

Est. Cost

£250–£450

OBD Codes

P0620P0622

Component Diagram

Electrics

Typical layout and location for the Electrics assembly.

Reference Illustration

Symptoms

Red battery warning light on dashboard
'Charging System Fault' message
Systems shutting down (radio, power steering) as battery depletes
Car fails to start

Root Cause

The internal voltage regulator or diode pack on the alternator burns out due to heat and age. Occasionally, a slipping auxiliary belt causes the issue.

How To Fix

Test battery voltage with engine running (should be 13.8V - 14.7V).
If below 12.5V, replace the alternator.
Always replace the auxiliary drive belt at the same time.
Cost: £250-450

Estimated Repair Costs

Repair Option	Est. Cost (GBP)
DIY (parts only)	£100–£180
Independent Garage	£250–£450
Main Dealership	£400–£720

Other Faults on This Variant

Water Pump / Coolant SIlca Bag Rupture

Critical

2013-201940,000–90,000 miles£800–£1500

The coolant expansion tank contains a 'Silica bag' designed to extend coolant life. This bag frequently bursts, sending silica gel through the engine and destroying the water pump and heater matrix.

Haldex Gen 5 Pump Failure (quattro models)

Severe

2013-201950,000–80,000 miles£400–£500

On quattro models, the Generation 5 Haldex unit frequently fails because VW/Audi removed the filter present on older generations.

DSG DQ250 Dual Mass Flywheel Wear

Moderate

2013-201980,000–140,000 miles£700–£1000

The 6-speed wet DSG gearbox (DQ250) is highly reliable, but the Dual Mass Flywheel (DMF) attached to it is a consumable item that fails predictably.

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