Mercedes-Benz GLA Alternator: Specs, Fitment & Common Faults
On the GLA, a battery warning light was genuinely initially quoted at £420 for a full alternator replacement, but the actual cause was a seized tensioner pulley bearing — the alternator itself was completely fine.
Illustration for editorial purposes
Opens live listings in a new tab.
OEM Part Number: confirm via VIN — alternators (aftermarket) 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, 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 9091076 (175 A, freewheel pulley, 6 ribs, 55 mm, remanufactured, COM plug). |
|---|---|
| Outputs & variants | 150 A five-rib 52-54 mm units for the M270 petrol GLA 180/200/250 (freewheel or rigid pulley); 175 A six-rib 55 mm freewheel units with a COM/LIN2 plug for the OM651 diesel GLA 200 d/220 d. The same parts fit the W176 A-Class and C117 CLA. |
| Genuine (OE) numbers quoted | 0125711043 (AS-PL A0811S); 0125711028 (AS-PL A0531S); 0125711030 (AS-PL A0545S); 0125711093 (AS-PL A0545(SEG)). |
| Fitment notes | Rib count separates petrol (5) from diesel (6), so check the old pulley and belt; all engines have start-stop with a LIN-controlled alternator, and Bosch, Valeo and Walker exchange units carry core charges of £25-£50. |
Mercedes-Benz GLA Alternator: Often Blamed on the Battery Instead
Because a weak Mercedes-Benz GLA battery and a dying alternator both cause dim lights, slow starts and charge that won't hold, it's an easy mistake to replace the wrong one first. That mix-up sends plenty of people back to the garage a few weeks later, the real fault still there.
Mercedes-Benz GLA Alternator: What It Does
Every time the Mercedes-Benz GLA's engine runs, the alternator is generating the electricity that charges the battery and directly feeds the electrical systems. A properly working alternator leaves the battery mostly responsible for engine starts and short demand spikes — not for running the electronics unaided.
Mercedes-Benz GLA Alternator: Watch: Replacing It
same MFA platform and M270 engine
Opens live listings in a new tab.
A Genuinely Alarming, Honest Real Account Worth Knowing — Mercedes-Benz GLA Alternator
If the battery warning light has come on, this is genuinely worth knowing before paying for a full alternator replacement: one documented case saw a battery warning light initially quoted at £420 fully fitted for a complete alternator replacement, but the actual root cause turned out to be a seized tensioner pulley bearing rather than a genuine alternator failure. Once this bearing loses its lubrication, the drive belt begins sliding and eventually destroys itself, stopping the alternator being driven entirely and triggering the exact same warning light, even though the alternator itself is completely fine.
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 GLA 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.