Audi A6 Alternator: Specs, Fitment & Common Faults

On the A6, a broomstick technique can genuinely help isolate whether a noise comes from the alternator, before assuming a battery replacement will fix it.

Illustration for editorial purposes

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OEM Part Number: 078903016H

Accuracy note: confirmed for C5/C6 generation, 2.7/2.8L V6 — this same reference is shared with the A4, allroad, and S4 of the same era.

2.7L/2.8L V6	Audi OEM: 078903016H
Diesel/other engine variants	Genuinely different alternator references apply across the A6's wide engine range — confirm your exact engine code before ordering

Audi A6 Alternator: Often Blamed on the Battery Instead

Early on, a weak Audi A6 battery and a dying alternator look almost identical — dim lights, sluggish starts, a car that won't hold its charge — which is exactly why so many people fit a new battery and end up back at the garage weeks later, the actual fault still unaddressed.

Before you buy: alternator output rating varies by engine size and trim, particularly on cars with more onboard electronics. Always confirm against your VIN before ordering.

Audi A6 Alternator: What It Does

On the Audi A6, while the engine runs, the alternator generates the electricity that charges the battery and powers the car's electrical systems directly. With a healthy alternator, the battery's real job becomes starting the engine and covering brief demand spikes, rather than running the electronics on its own.

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A Genuinely Useful Piece of Context Worth Knowing About Alternator Diagnosis — Audi A6 Alternator

If you're trying to confirm whether a noise is genuinely coming from the alternator, this is genuinely worth trying: touching one end of a wooden broomstick to the alternator housing, with the other end held close to your ear, can help you hear the noise much more clearly.

A genuinely important, real account worth knowing before replacing another battery: going through more than one battery in a short period is a strong sign the alternator isn't charging properly, worth testing its actual voltage output directly with a multimeter rather than continuing to replace batteries — a healthy reading with the engine running should be roughly 13.8 to 14.8 volts.

It's also genuinely worth knowing that related Audi models fitted with the 48V mild hybrid system have documented alternator failures specifically tied to this system, with a confirmed US extended warranty covering the issue.

Audi A6 Alternator: Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Alternator Guide for symptoms to watch for (plus a genuinely useful two-minute test to confirm it's not the battery instead), confirming the right amperage and fitment against your VIN, and which brands are worth trusting.

More Audi Alternator

The same part, covered across other Audi models.