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 (genuine alternator — confirm via VIN) — aftermarket alternators Valeo 439800 / Hella 8EL 015 637-451
| Alternators (aftermarket) | Valeo 439800 (180 A, freewheel pulley, 6 ribs, 57 mm, new); Valeo 440680 (180 A, freewheel, 6 ribs, 57 mm, remanufactured exchange, four-point mounting, core charge £50.24); Valeo 444215 (180 A, rigid V-ribbed pulley, 6 ribs, 56 mm, remanufactured exchange, core charge £50.24); Valeo 444733 (180 A, freewheel, 6 ribs, 51 mm, remanufactured exchange, core charge £50.24); Hella 8EL 015 637-451 (180 A, rigid V-ribbed pulley, 6 ribs, 56 mm, new); AS-PL A0576S (150 A, freewheel, 6 ribs, 49.5 mm, new, plug PL_2306); AS-PL A3491S (230 A, freewheel, 6 ribs, 56 mm, new, plug PL_2306); Ridex 4G1139 (180 A, freewheel, 6 ribs, 49 mm, new, LIN2 plug 238, excludes vacuum pump) |
|---|---|
| Outputs & variants | 180 A is the dominant fitment across the 2.0 TDI, 3.0 TDI and 3.0 TFSI engines; 150 A units (AS-PL A0576S, Mapco 13218, Stardax STX102208) cover the 2.0 TFSI petrol, 140 A (Valeo 439814) the entry-level cars, and 200 A and 230 A units (AS-PL A3510S, BV PSH 205.546.200.000, AS-PL A3491S) the high-output diesels and cars with heavy electrical loads. Both freewheel and rigid pulleys appear at 180 A, so the old unit must be checked. |
| Genuine (OE) numbers quoted | 0125711130 (AS-PL A0576S), FG20S011 (AS-PL A3510S), 0121715176 (AS-PL A0409), FG20S018 (AS-PL A3493S), FG23S035 (AS-PL A3491S), FG20S014 (AS-PL A3490S), FG20S015 (AS-PL A3486S). |
| Fitment notes | Pulley diameters range from 49 mm to 57 mm and mounting is four-point on the Valeo units, so matching the original is essential; the Ridex units are supplied without the vacuum pump, and the remanufactured Valeo units carry a £50.24 core charge refunded when the old alternator is returned. |
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.
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.
Audi A6 Alternator: Watch: Replacing It
C7 3.0 TDI, also covers A7/Q5/Q7 on the same engine
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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.
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.