Fiat 500L Alternator: Specs, Fitment & Common Faults

On the 500L, a genuinely useful DIY access technique helps reach the notoriously awkward top mounting bolt when replacing the alternator.

Illustration for editorial purposes

Find Fiat 500L Alternator Here!

Opens live listings in a new tab.

OEM Part Number: 51859041

Accuracy note: genuine reference varies by engine — confirm your exact spec before ordering.

1.3 Multijet diesel	Fiat OEM: 51993603 — shared with 500X, Tipo
1.4 petrol	Fiat OEM: 51859041 — genuinely a different reference from the diesel unit

A Genuinely Useful, Real DIY Access Technique Worth Knowing — Fiat 500L Alternator

If you're replacing the alternator yourself and struggling to reach the top mounting bolt, this is genuinely worth knowing: disconnecting the "dog bone" engine mount and wedging the engine forward slightly, away from the firewall, creates just an extra inch of working space — but that single extra inch has been described as making all the difference when trying to reach this specific bolt on related models.

A genuinely useful diagnostic technique worth knowing: pressing one end of a long screwdriver against the alternator housing and the other end near your ear, similar to a stethoscope, can help isolate whether noise is genuinely coming from the alternator itself.

It's also genuinely worth knowing it's worth briefly running the engine with the auxiliary drive belt removed, if safe and practical, since this rules out the belt itself as the source of a noise you might otherwise blame on the alternator.

Fiat 500L Alternator: Often Blamed on the Battery Instead

On the Fiat 500L, 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.

Fiat 500L Alternator: What It Does

The Fiat 500L'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.

Find Fiat 500L Alternator Here!

Opens live listings in a new tab.

Fiat 500L 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 Fiat Alternator

The same part, covered across other Fiat models.