A Guide to Replacing the Alternator on Your 2013-2021 Subaru WRX
Everything a WRX owner needs to know about choosing the right new aftermarket alternator.
- Symptoms include dimming lights, a battery warning light, and whining noises from the engine.
- The alternator is a DIY-friendly replacement, located on top of the engine for easy access.
- A quality new aftermarket brand like ACDelco or Remy offers a reliable alternative to the expensive OEM part.
- In some cases, a failing alternator can cause false engine misfire codes (P0300) due to voltage fluctuations.
Is Your WRX's Alternator Failing?
The alternator is a hard-working part that eventually wears out. In the 2013-2021 Subaru WRX, symptoms of a failing alternator are often noticeable and shouldn't be ignored. Driving with a bad alternator can leave you stranded once the battery's reserve power is depleted. Be aware of the common warning signs.
🎬 Watch this guide to diagnosing a failing Subaru alternator.Key Symptoms of a Bad Alternator:
- Battery Warning Light: The most obvious sign is the battery-shaped warning light on your dashboard. This indicates a problem in the charging system.
- Dimming or Flickering Lights: Headlights and interior lights may dim, especially at idle, and then brighten as you rev the engine. You might also notice the lights pulsing or flickering.
- Electrical Gremlins: Modern cars like the WRX have many electronics. A failing alternator can cause strange issues like the radio cutting out, power windows moving slowly, or other random electrical bugs.
- Whining or Grinding Noises: A high-pitched whining or grinding sound from the engine bay that changes with engine RPM often points to failing bearings inside the alternator.
- Engine Stalling: The engine needs electricity to run. If the alternator fails completely, the car will run on battery power for a short time before it stalls.
OEM vs. New Aftermarket Alternators
When it's time for a replacement, you have a choice between Original Equipment Manufacturer (OEM) and aftermarket parts. The original alternator in your WRX is typically a high-quality Denso unit.
- OEM (Subaru/Denso): These parts are identical to what your car came with from the factory. They offer proven reliability and a perfect fit, but come at a high cost, often several hundred dollars more than aftermarket options.
- New Aftermarket: This is where the value lies for many owners. Quality can vary, so it's important to choose a reputable brand. A good aftermarket alternator can provide reliability close to OEM for a fraction of the price. The brands available in our inventory (ACDelco, Remy, MPA, BBB Industries) offer a range of options.
Choosing the Right Aftermarket Brand
Not all aftermarket brands are created equal. For a performance vehicle like the WRX, it's best to avoid the cheapest options, which may have lower quality internal components and a shorter lifespan.
- Premium Aftermarket (e.g., ACDelco, Remy): These are well-known brands with a reputation for quality control and reliability. They often use new components and rigorous testing to ensure performance that meets or exceeds OEM standards. An ACDelco Gold or a new Remy alternator is a solid choice for reliability without the OEM price tag.
- Standard Aftermarket (e.g., MPA, BBB Industries): These brands provide a cost-effective solution and are often available as remanufactured units. While they can be a good value, it's important to check the warranty and ensure the part has been thoroughly tested.
Cost of Replacing a WRX Alternator
The cost can vary significantly based on the part you choose and whether you do the work yourself. The alternator on the WRX is located at the top of the engine and is relatively easy to access, making it a feasible DIY project for those with some mechanical skill.
🎬 See this step-by-step 2015-2021 WRX alternator replacement walkthrough.| Item | Estimated Cost |
|---|---|
| New OEM Part | $500 - $800+ |
| New Aftermarket Part | $140 - $245 |
| Remanufactured Part | $110 - $200 |
| Shop Labor | $150 - $300 |
Frequently Asked Questions (FAQ)
How long should an alternator last on a Subaru WRX?
An original alternator can last well over 100,000 miles. However, factors like driving conditions, climate, and electrical load (from accessories like a large stereo system) can affect its lifespan. High heat from the turbocharged engine can also contribute to wear over time.
Can I upgrade my WRX alternator?
Yes, high-output alternators are available, offering higher amperage than the stock 110-amp unit. An upgrade is only necessary if you have added significant electrical accessories, such as a powerful audio system, competition lighting, or other high-draw components. For a stock or lightly modified WRX, the standard output is sufficient.
🎬 Watch a replacement tutorial for 2008-2014 WRX models.Is a remanufactured alternator a good choice?
A quality remanufactured alternator from a reputable brand like Denso or ACDelco can be an excellent choice. These units are rebuilt with new bearings, brushes, and regulators, and are tested to meet original specifications. They offer a good balance of quality and cost, but be sure they come with a good warranty.
Are there any recalls on the 2013-2021 WRX alternator?
No, there are no specific recalls for the alternator on the 2013-2021 Subaru WRX or STI. There was a recall for a backup light switch on some 2015-2021 STI models, but this is unrelated to the alternator itself.
Helpful Videos
Technical Specifications
OEM Part Numbers: 23700AA680 23700AA681 23700AA870 23700AA871
Amperage: 110A, Voltage: 12V, Pulley: 5-Groove.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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