Ford Focus Mk3 Alternator: Specs, Fitment & Common Faults

The simple multimeter test that confirms whether it's genuinely the alternator — plus why some replacement units develop the exact same fault.

Generation covered: this guide is for the third-generation Focus, built 2011–2018 (commonly the 2014–2018 registered examples still in daily use). The newer Mk4 Focus (2018–) uses different part numbers throughout — check your V5C logbook or VIN if you're unsure which generation you have.

Illustration for editorial purposes

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A Simple Test to Confirm the Alternator Before Replacing It

Before paying for a replacement, it's worth confirming the alternator is genuinely the problem: with the engine running, a multimeter across the battery terminals should read roughly 13.8-14.5V — readings notably below this suggest the alternator isn't charging properly, while readings significantly above 14.5V suggest a failing voltage regulator, a related but different fault. A whining noise that gets noticeably louder when heavy electrical loads switch on (headlights, heated rear window, air conditioning on full) is also a strong practical indicator worth checking before assuming the worst.

Worth knowing when buying a replacement: Several Focus owners report remanufactured or budget aftermarket alternators developing the same whining noise shortly after fitting — in one documented case across three separate replacement units. A well-reviewed reconditioned unit from a specialist, or a low-mileage genuine used alternator, is frequently a safer bet than the cheapest reman alternative.

Ford Focus Mk3 Alternator: Often Blamed on the Battery Instead

On the Ford Focus Mk3, a weak battery and a failing alternator produce almost identical symptoms at first — dim lights, slow starts, a car that won't hold charge — which is exactly why so many people replace the battery, only to be back at the garage a few weeks later with the real culprit untouched.

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.

Ford Focus Mk3 Alternator reference plate

OEM Part Number: CV6Z-10346-B

Accuracy note: alternator output (amperage) varies by engine and specification — always match both the part number and the amp rating printed on your existing unit's casing before ordering, since fitting a lower-output alternator than your car needs can leave it unable to keep the battery charged.

1.6 Ti-VCT / 2.0 GDI petrol (120A)	Ford OEM: CV6Z-10346-B
2.0 non-turbo, 6-speed automatic (150A)	Ford OEM: BV6Z-10346-F
Higher-spec trims with heated screen/premium audio	150A unit likely fitted as standard — confirm via the amp rating on your existing alternator

The Mk3 Focus most commonly used a 120-amp alternator for standard-spec petrol models, with a 150-amp unit reserved for higher electrical loads. Diesel and ST variants use different mounting configurations entirely, so always cross-check the physical connector and pulley type as well as the part number.

Ford Focus Mk3 Alternator: What It Does

The Ford Focus Mk3's alternator generates electricity while the engine runs, charging the battery and powering the car's electrical systems directly. A healthy alternator means the battery is mostly there for starting the engine and covering brief demand spikes — not for actually running the car's electronics on its own.

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Ford Focus Mk3 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 Ford Alternator

The same part, covered across other Ford models.