Mercedes-Benz A-Class Alternator: Specs, Fitment & Common Faults
A genuinely useful diagnostic technique: with the engine running, a long screwdriver held to your ear against each suspect pulley can isolate exactly which component is making a noise — plus a simple test spinning each pulley by hand with the belt removed.
Illustration for editorial purposes
Opens live listings in a new tab.
OEM Part Number: A0009068106 (genuine alternator — confirm via VIN) — aftermarket alternators Bosch 1 986 A01 041 / Valeo 444471
| Alternators (aftermarket) | Bosch 1 986 A01 041 (150 A, freewheel pulley, 5 ribs, 52.3 mm, new, plug 181, excludes vacuum pump); Bosch 0 986 082 150 (150 A, rigid multi-rib pulley, 5 ribs, 54 mm, remanufactured exchange, plug PL166, core charge £47.03, excludes vacuum pump); Valeo 444471 (175 A, freewheel pulley, 6 ribs, 55 mm, remanufactured exchange, B+/LIN2, core charge £50.24); Hella 8EL 011 713-551 (150 A, freewheel pulley, 5 ribs, 53 mm, new); AS-PL A0545S (150 A, freewheel pulley, 5 ribs, 52 mm, new, plug PL_2306); AS-PL A0811S (175 A, freewheel pulley, 6 ribs, 55 mm, new, plug PL_2306); Rotovis 9090817 (150 A, freewheel pulley, 5 ribs, 52 mm, remanufactured, COM plug). |
|---|---|
| Outputs & variants | 150 A five-rib units (52-54 mm, COM/LIN plug) suit the M270 1.6 and 2.0 petrol engines, offered with either a freewheel or a rigid pulley; 175 A six-rib 55 mm freewheel units with a COM/LIN2 plug suit the OM651 1.8 and 2.2 diesels and higher-spec cars. |
| Genuine (OE) numbers quoted | 0125711030 (AS-PL A0545S); 0125711028 (AS-PL A0531S); 0125711043 (AS-PL A0811S); 0125711093 (AS-PL A0545(SEG)). |
| Fitment notes | All W176 engines have start-stop and a LIN-controlled alternator, so the plug type (COM/LIN) must match and the rib count (5 or 6) must match the belt; Bosch and Valeo exchange units carry a core charge of £47-£50 refunded on return of the old unit. |
Mercedes-Benz A-Class Alternator: Often Blamed on the Battery Instead
On the Mercedes-Benz A-Class, a failing alternator and a simply weak battery share almost the same symptom set at first: dim lights, sluggish starts, charge that won't hold. Mixing the two up is common, which is why plenty of people replace the battery only to find themselves back at the garage shortly after.
Mercedes-Benz A-Class Alternator: What It Does
The Mercedes-Benz A-Class's electrical systems and battery charging both depend on the alternator generating electricity whenever the engine runs. If it's healthy, the battery's job shrinks down to starting the engine and handling brief surges in demand, not powering everything else on its own.
Mercedes-Benz A-Class Alternator: Watch: Replacing It
W176 A180
Opens live listings in a new tab.
A Genuinely Useful Diagnostic Technique Worth Knowing — Mercedes-Benz A-Class Alternator
If a squeaking or squealing noise from the drive belt area is proving difficult to pin down, this is genuinely worth trying: with the engine running, placing one end of a long screwdriver directly onto each suspect pulley or component, such as the alternator, water pump, or power steering pump, and the other end to your ear, is a genuinely simple way to isolate exactly which specific component is the source of the noise, rather than guessing or replacing parts speculatively. With the belt removed entirely, each individual pulley should also turn easily and smoothly by hand — one that feels stiff, notchy, or has noticeable play points directly to that specific bearing as the likely culprit.
It's also genuinely worth knowing that the pulley driving the alternator on many of these engines is a genuine one-way clutch mechanism, allowing the alternator's rotor to coast down gently to a stop rather than being abruptly halted.
Mercedes-Benz A-Class 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 Mercedes-Benz Alternator
The same part, covered across other Mercedes-Benz models.