Subaru Crosstrek Alternator: Specs, Fitment & Common Faults
On the Crosstrek, removing the alternator belt and starting the engine genuinely confirms or rules out the alternator entirely as the source of a noise.
Illustration for editorial purposes
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OEM Part Number: 23700AB051 (genuine alternator — confirm via VIN) — aftermarket alternators Bosch 1 986 A01 427 / AS-PL A5392S
| Alternators (aftermarket) | Bosch 1 986 A01 427 (130 A, freewheel clutch pulley, 6 ribs, 52.5 mm, new, plug 163, without vacuum pump, £7.31 core charge); AS-PL A5392S (150 A, freewheel, 7 ribs, 55 mm, new Standard Line, plug PL_3308, OE A2TX2381A); AS-PL A5349 (170 A, freewheel, 7 ribs, 55 mm, new Standard Line, plug PL_3308, OE A3TX0781); AS-PL A5252 (110 A, rigid pulley, 6 ribs, 55 mm, new Premium Line Mitsubishi-sourced, plug PL_3401, OE A3TG6691); AS-PL A5126 (110 A, rigid pulley, 6 ribs, 55 mm, new Premium Line Mitsubishi-sourced, plug PL_3308, OE A2TL0291); AS-PL A6791S (150 A, freewheel, 6 ribs, 52.5 mm, new Standard Line, plug PL_1100, OE 104211-4480, GT generation only); Ridex 4G1423 (150 A, freewheel, 7 ribs, 55 mm, new, plug C/S/L, without vacuum pump); Rotovis 9091934 (150 A, freewheel, 6 ribs, 55 mm, remanufactured, plug C/S/L) |
|---|---|
| Outputs & variants | 130 A freewheel 6-rib (Bosch 1 986 A01 427, Denso 104211-4480 pattern on the 2017-on GT); 200 A Valeo-pattern unit (AS-PL A3719, OE 439866) also listed but not a typical UK XV fitment |
| Genuine (OE) numbers quoted | A2TX2381A (AS-PL A5392S); A3TX0781 (AS-PL A5349); A3TG6691 (AS-PL A5252); A2TL0291 (AS-PL A5126); 104211-4480 (AS-PL A6791S); 439866 (AS-PL A3719) |
| Fitment notes | Match amperage, pulley type and plug. |
Subaru Crosstrek Alternator: Often Blamed on the Battery Instead
Early on, a weak Subaru Crosstrek 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.
Subaru Crosstrek Alternator: What It Does
On the Subaru Crosstrek, 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.
Subaru Crosstrek Alternator: Watch: Replacing It
Aftermarket high-output unit but shows full removal/fit on 2015 XV
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A Genuinely Definitive, Real Diagnostic Technique Worth Knowing — Subaru Crosstrek Alternator
If you're chasing a whine or squeal that might be coming from the alternator, the power steering pump, or a belt tensioner, this is genuinely worth knowing: removing the alternator's drive belt entirely and briefly starting the engine to see whether the noise disappears is a genuinely definitive way to confirm or rule out the alternator itself, since with the belt removed the alternator physically cannot be spinning or making noise.
It's also genuinely worth knowing that some noise specifically under a genuinely heavy electrical load has been described as difficult to reproduce except under loads well beyond what the car would typically draw at idle — worth bearing in mind that not every noise heard only under heavy load necessarily indicates a fault.
Subaru Crosstrek 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 Subaru Alternator
The same part, covered across other Subaru models.