Lexus RX Alternator: Specs, Fitment & Common Faults
A genuinely useful, real diagnostic technique: using a screwdriver as a makeshift stethoscope helps pinpoint exactly which pulley is actually making a noise before assuming it's the alternator — plus an important safety warning about driving on a confirmed alternator failure.
Illustration for editorial purposes
Opens live listings in a new tab.
OEM Part Number: 27060-20300 (as quoted in catalogue listings — confirm via VIN) — aftermarket alternators AS-PL A3710 Valeo
| Alternators (aftermarket) | AS-PL A3710 Valeo (180 A, freewheel pulley, 6 ribs, 56 mm, new Premium Line, plug PL_2306); Rotovis 9091619 (150 A, freewheel pulley, 6 ribs, 55 mm, remanufactured, COM plug); AS-PL A6737S (150 A, freewheel pulley, 6 ribs, 55 mm, new, plug PL_2306); AS-PL A3801S (150 A, freewheel pulley, 6 ribs, 53 mm, new, plug PL_2306); Autoelectro AEK4457 (180 A, 6 ribs, new, B+/LIN2 plug, core charge £125.59); Walker WAL01826 (150 A, freewheel pulley, 6 ribs, 55 mm, remanufactured, plug 0238, core charge £50.24); DRI 2353721502 (150 A, freewheel pulley, 6 ribs, 55 mm, remanufactured exchange, plug 0238, core charge £45.27). |
|---|---|
| Outputs & variants | The RX 200t/300 2.0 turbo uses the 150 A six-rib 55 mm freewheel unit with a LIN plug; the 3.5 V6 RX 350 is covered by 150 A and 180 A six-rib units (AS-PL A3801S, A3710/Valeo); the 100-130 A six-rib rigid-pulley listings (AS-PL A6146, A6282, A6809S) are carried over from earlier Toyota V6 applications. |
| Genuine (OE) numbers quoted | 104211-8860 (AS-PL A6737S); FGN15S116 (AS-PL A3801S); 1042103750 (AS-PL A6146); 104210-3120 (AS-PL A6282); 104210-5010 (AS-PL A6465S); 104210-3450 (AS-PL A6287); 104210-4470 (AS-PL A6294); 27060-20300 (AS-PL A6809S); 439737 (AS-PL A3710 Valeo). |
| Fitment notes | The RX 450h hybrid has no belt-driven alternator, so these fit the petrol 200t, 300 and 350 only; most quoted parts are 14 V output for a 12 V system, and exchange units from Walker, DRI and Autoelectro carry core charges of £25-£126 on top of the price. |
Lexus RX Alternator: Often Blamed on the Battery Instead
On the Lexus RX, dim lights, slow starts, a battery that won't hold charge — these symptoms point equally to a weak battery or a failing alternator, and that overlap is why so many replacements target the wrong part first, with the real problem only surfacing weeks later.
Lexus RX Alternator: What It Does
Electricity generation while the Lexus RX's engine is running is the alternator's job, charging the battery and directly powering the electrical systems. When it's working properly, the battery mostly just handles engine starting and short demand spikes, not day-to-day electrical load.
Lexus RX Alternator: Watch: Replacing It
RX350 petrol V6
Opens live listings in a new tab.
A Genuinely Useful, Real Diagnostic Technique Worth Trying — Lexus RX Alternator
If you're chasing an engine bay noise and trying to work out whether the alternator is genuinely the cause, this is genuinely worth trying: holding a screwdriver or length of hose against various pulleys and components while the engine runs, with your ear against the other end, can help isolate exactly where a noise is genuinely coming from. If this technique doesn't pick up the noise specifically at the alternator itself, this is a real sign the noise probably isn't the alternator at all, worth checking other pulleys and the belt tensioner more closely instead.
It's also genuinely worth knowing that with the belt removed, manually checking each pulley and component for play by pushing, pulling, and rocking it in different directions can help identify which specific part is genuinely worn, since the alternator itself may show no play at all while a completely different component does.
Lexus RX 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 Lexus Alternator
The same part, covered across other Lexus models.