Your Subaru is more than just a vehicle—it’s a part of your daily life, and keeping it safe, reliable, and running smoothly should always be a priority. One crucial component that often gets overlooked is the alternator. As part of your Subaru’s powertrain system, the alternator is responsible for generating the electricity needed to run your vehicle’s accessories, lights, and even the starter when you fire up the engine.
Over time, alternators can wear out or lose efficiency, and if they’re no longer performing at full capacity, replacement becomes necessary. The key is catching the warning signs before the alternator fails completely—helping you avoid costly repairs and roadside breakdowns. In this article, we’ll highlight the most common signs of alternator trouble, and what you can do to prevent early failure and keep your Subaru in peak condition.
Read on to learn how to spot the signs of a failing alternator in your Subaru—before it leaves you stranded at home or on the road.
Dim Lights
If your headlights appear dimmer than usual, or your radio and stereo system sound weaker, your alternator could be to blame. The alternator powers your vehicle’s electrical systems, including the lights, infotainment, and interior electronics. When it begins to fail, it can no longer deliver consistent power, leading to flickering or dim lighting and reduced performance from accessories.
These symptoms won’t go away just by turning up the volume or switching to brighter bulbs—because the underlying issue is a lack of power generation. If you’re noticing these signs, it’s best to have your alternator inspected before it fails completely.
Dead Battery
A dead battery is one of the most common signs that your alternator may be failing. If your vehicle struggles to start—or won’t start at all—and the electrical systems seem underpowered, the alternator might not be supplying enough charge to keep the battery functioning.
While the battery warning light often appears on the dashboard, it doesn’t always point directly to a battery issue—it can also indicate a problem with the charging system, including the alternator. To rule out minor issues, try starting your car with minimal electrical load (e.g., turning off the lights, radio, and climate control). If the problem persists, it’s wise to have the alternator professionally tested before replacing the battery. This could save you from buying a new battery that won’t solve the root cause.
Whirring or Buzzing Noises from the Engine
If you notice unusual whirring, buzzing, or grinding sounds coming from under the hood, it could be a sign that your alternator is wearing out. These noises may indicate a failing bearing, a loose belt, or internal components starting to break down.
While odd sounds don’t always point to the alternator, they should never be ignored. If these noises are persistent or increase with engine speed, it’s best to have your vehicle inspected by a qualified technician. Catching the issue early could prevent further damage and save you from a more expensive repair down the road.
Unusual Electrical Bugs
If you start experiencing strange electrical behavior, such as headlights turning on when you activate the wipers, taillights not working, windows flickering, or a sudden cluster of warning lights appearing on your dashboard, your alternator could be the culprit.
As the alternator begins to fail, it can no longer provide consistent power to the vehicle’s electrical systems. High-demand components like the radio, air conditioning, and lighting systems begin to draw more power than the alternator can supply—causing your battery to drain rapidly and leading to increasingly erratic behavior across multiple systems.
These electrical bugs may seem random, but they often point to a deeper charging system issue. Don’t ignore them—get your alternator checked before a small glitch turns into a full electrical failure.
