Honda Civic Alternator: Specs, Fitment & Common Faults

A genuinely valuable, real money-saving story: a new alternator and belt didn't fix a whine — the actual cause was a known tensioner pulley failure, resolved cheaply without replacing the alternator again.

Illustration for editorial purposes

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OEM Part Number: 31100-5PA-A01 (genuine alternator — confirm via VIN) — aftermarket alternators Denso DAN1326 / AS-PL A6566S

Accuracy note: Covers the Honda Civic (2012-2017) as listed in the UK aftermarket catalogues. Alternators are sold by output (amps), pulley type and plug, and the same model usually has two or three units depending on engine, start-stop and the electrical load of the trim — a 120 A unit on a car built for 150 A will undercharge, and a rigid pulley on a car designed for a freewheel clutch pulley will shred belts. The references below are UK aftermarket catalogue listings for this generation, labelled by brand; many are remanufactured exchange units that carry a core charge until the old alternator is returned. Genuine numbers are shown only where a listing quotes one. Check the amp rating, pulley and plug stamped on the old unit, or confirm via VIN, before ordering.

Alternators (aftermarket)	Denso DAN1326 (150 A, freewheel clutch pulley, 7 ribs, 65 mm, new, OE quality); AS-PL A6566S (150 A, freewheel clutch pulley, 7 ribs, 65 mm, new, PL_1000 plug); AS-PL A6667S (150 A, freewheel clutch pulley, 7 ribs, 65 mm, new, PL_1000 plug); AS-PL A6413S (130 A, freewheel clutch pulley, 7 ribs, 65 mm, new, PL_4801 plug); AS-PL A5117 (95 A, rigid belt pulley, 6 ribs, 60.5 mm, new, PL_1000 plug); Ridex 4G1164 (150 A, freewheel clutch pulley, 7 ribs, 65 mm, new, B+ M8, excludes vacuum pump); Ridex Reman 4G1164R (150 A, freewheel clutch pulley, 7 ribs, 65 mm, reman exchange, B+ M8, core charge GBP 30.14); Rotovis 9091416 (150 A, freewheel clutch pulley, 7 ribs, 65 mm, reman, COM plug).
Outputs & variants	a 130 A seven-rib version also appears.
Genuine (OE) numbers quoted	AS-PL A5117 quotes A5TJ0191ZC; AS-PL A6667S quotes 104211-8040; AS-PL A6566S quotes 104210-1650; AS-PL A6413S quotes 104210-1150.
Fitment notes	Diesel and petrol Civics use completely different alternators, seven-rib 150 A freewheel against six-rib 95 A rigid, so check the engine code first; the diesel 150 A units are offered with either a 65 mm or 70 mm pulley; Ridex and Walker exchange units carry a refundable core charge while the AS-PL A6566PR reman is sold without a deposit; Casco CAL40430AS is listed only as a replacement for Denso original fitment.

A Genuinely Valuable, Real Money-Saving Story Worth Knowing — Honda Civic Alternator

If you've already replaced the alternator and the drive belt but a whine persists, this is genuinely worth knowing before assuming the new alternator is faulty: one documented case saw exactly this happen, with the actual cause eventually identified as the auxiliary belt tensioner pulley — a known failure point on some engines in this range, separate from the alternator itself. The pulley alone (not the entire tensioner assembly) was sourced cheaply and fitted, resolving the whine completely. If a new alternator hasn't fixed a whine, it's genuinely worth having the tensioner and idler pulleys specifically checked before assuming you've received a faulty replacement part.

A genuinely useful diagnostic distinction worth knowing: a whine that's present when the engine is running but changes character or disappears entirely above certain RPM ranges, particularly one that's more noticeable during acceleration specifically, points toward a belt-driven pulley bearing issue rather than the alternator's internal bearings, which tend to produce a more consistent whine proportional to engine speed throughout the rev range.

It's also worth knowing that alternator whine is sometimes confused with an unrelated, genuinely different noise from a poor electrical connection or grounding issue heard through the car's audio system — if the whine changes pitch with engine RPM specifically when the stereo is on, but not when it's off, this points toward an audio system grounding issue entirely separate from the alternator itself.

Honda Civic Alternator: Often Blamed on the Battery Instead

On the Honda Civic, 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.

Honda Civic Alternator: Watch: Replacing It

🎬 Watch: How to Replace Alternator 2012-2015 Honda Civic 1.8L I4

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9th-gen 1.8 petrol

Before you buy: alternator output rating varies by engine size and trim, particularly on cars with more onboard electronics. Always confirm against your VIN before ordering.

Honda Civic Alternator: What It Does

The Honda Civic'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.

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Honda Civic 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 Honda Alternator

The same part, covered across other Honda models.