Welcome to On Site Auto Repair!
Our Services
Complete Auto Repair Services — Done Right the First Time
From brake and transmission repair to diagnostics and routine maintenance, our certified mechanics handle all makes and models with precision, honesty, and fast turnaround.
Serving Santa Rosa Since 2011
★★★★★ 4.8/5 (100+ Reviews)
Complete Auto Repair Services in Santa Rosa
From routine maintenance to complex repairs, we handle it all with precision and care. Trust our certified mechanics to keep your vehicle running smoothly and safely.
Brake Services
- Brake pads, rotors, fluid replacement
- “Starting at $89”
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Transmission Repair
- Automatic & manual transmission service
- “Free diagnostic”
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Engine Repair & Diagnostics
- Automatic & manual transmission service
- “Free diagnostic”
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Heating & AC Service
- Climate control repair, refrigerant service
- “Stay comfortable year-round”
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Steering & Suspension
- Shocks, struts, alignment service
- “Smooth, safe driving”
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Cooling System Service
- Radiator repair, coolant flush
- “Prevent overheating”
Auto Repair Brand
Toyota Repair
Honda Repair
Ford Repair
Chevrolet Repair
Nissan Repair
Mercedes Repair
Lexus Repair
Acura Repair
Infiniti Repair
Kia Repair
Hyundai Repair
Subaru Repair
Mazda Repair
Volkswagen Repair
Contact Info
Location
363 W 9th St B & C
Santa Rosa, CA 95401
Phone
707-326-8655
Hours
- Monday-Friday: 8:00 AM - 5:30 PM
- Saturday: 8:00 AM - 4:00 PM
- Sunday: Closed
New Customer Special:
$25 Off First Service Over $100
Oil Change Special:
Full Synthetic Oil Change – $69.9
Free Brake Inspection
Complete brake system check at no charge
Latest News
Why Is My Coolant Light On in Sebastopol? What Low Coolant Actually Means for Your Engine
If your coolant warning light just came on near Sebastopol or anywhere in Sonoma County, don’t ignore it — low coolant can lead to serious engine damage fast. This guide explains what that light actually means, what causes coolant loss, and when you need to get it checked before a small problem becomes a very expensive one.
Why Are My Shocks and Struts Worn Out Already? What Healdsburg and Sonoma County Drivers Need to Know
If your ride feels bouncier than usual, or your car nose-dives when you brake, your shocks and struts might be telling you something. Here’s how to recognize the warning signs, why Sonoma County roads accelerate wear, and what to expect when you bring your vehicle in for suspension service.
How Do You Know When Your Car Battery Is Dying in Windsor or Santa Rosa? Signs, Tests, and What to Do
A dying car battery doesn’t always announce itself with a dramatic no-start. Learn the early warning signs Santa Rosa and Windsor drivers should watch for, what a proper battery test involves, and when it’s time to replace — before you’re stranded.
How Often Should You Change Your Transmission Fluid in Rohnert Park? Here’s What You Need to Know
Transmission fluid doesn’t get talked about as much as oil changes, but skipping it is one of the most expensive mistakes a driver can make. If you’re in Rohnert Park or anywhere in Sonoma County, here’s what you actually need to know about transmission fluid intervals, warning signs, and what happens when you wait too long.
Why Is My Car Shaking When I Drive? Steering and Suspension Warning Signs in Santa Rosa
If your car shakes, pulls to one side, or feels like it’s bouncing over every little bump, your steering or suspension is trying to tell you something. Here’s what those symptoms actually mean for Santa Rosa drivers — and when to get it looked at before a small problem becomes an expensive one.
Why Is My Car’s AC Blowing Warm Air in Petaluma? What’s Going On and How to Fix It
If your car’s AC is blowing warm air this summer, you’re not imagining it — and you’re definitely not alone in Petaluma or anywhere across Sonoma County. This article breaks down the most common reasons your AC stops cooling, what the warning signs mean, and when it’s time to bring it in for a proper diagnosis.
Why Is My Check Engine Light On in Santa Rosa? What It Actually Means and What to Do Next
That little amber light on your dashboard can mean anything from a loose gas cap to a failing catalytic converter — and most Santa Rosa drivers have no idea which one they’re dealing with. Here’s what the check engine light actually means, when it’s safe to keep driving, and when you need to pull over and call a shop right away.
Why Are My Brakes Squealing in Santa Rosa? What It Means and When to Get It Fixed
That high-pitched squeal when you hit the brakes is your car trying to tell you something — and in Santa Rosa, where hilly neighborhoods and long Highway 101 commutes put real strain on your braking system, it’s worth listening. This guide breaks down exactly what brake noise means, when it’s urgent, and what you can expect from an honest brake inspection.
Why Is My Car Overheating in Petaluma? What to Do and When to Get It Checked
If your temperature gauge is climbing or you’re seeing steam from under the hood around Petaluma or anywhere in Sonoma County, don’t ignore it. Overheating is one of the fastest ways to turn a minor repair into a major engine problem — here’s what’s actually happening, what to do in the moment, and when to bring it in.
Essential Hyundai maintenance tips for long-lasting performance
With regular maintenance, you can ensure that your Toyota performs at its best in the beautiful surroundings of Santa Rosa, CA. This guide offers imperative tips tailored to the unique driving conditions and climate in the area, helping you keep your vehicle in top...
Read More About Our Auto Mechanic Services
On Site Auto Repair in Santa Rosa is a full service auto mechanic shop. Our auto mechanics are certified and here to help you with all of your automotive repair needs. No auto repair job is too big or too small for On Site Auto Repair.We specialize in all types of auto repair, including: regular maintenance, break/fix, engine repair, troubleshooting and much more! If you are looking for honest and reliable auto mechanics, give us a call today. Ask us about our new customer specials
Vehicles are usually described as 5 or 6 “speed” meaning then have that many gear ratios to allow the vehicle to travel at the full range of speeds required and to make use of the engine’s output power as efficiently as possible. Due to their complexity, constant use and function within a vehicle’s operation, transmissions experience a lot of wear and tear. Add to this the fact that many owner’s forget to check and change the fluid on a regular basis and it’s easy to understand why so many people have transmission problems. At On Site Auto Repair in Santa Rosa, our transmission repair technicians can accurately diagnose, repair or replace your transmission. If your are looking for a reliable and honest transmission repair services company, give us a call today!
There are several warning signs that your vehicle can give you before your brakes may reach the point of potential failure or extensive repair. Whether composed of ceramic, semi-metallic, or organic materials, brake pads erode each time you depress the brake pedal. If the pads wear down too much without being replaced, the metal housing for the pads will make contact with the metal rotors (or drums), which may produce not only a safety issue but a situation where the rotors/drums are required to be replaced as a result of the prolonged contact of metal parts without the pad buffer. If you are in need of an affordable brake repair mechanic in Santa Rosa, please do not hesitate to schedule an appointment today!
Vehicle Inspection In Santa Rosa
The key to top notch automotive repair and troubleshooting lies in a thorough understanding of what’s actually going on under the hood. Sure, you know that a radiator keeps your engine cool, but understanding how it keeps it cool is the key to solving technical problems efficiently. If you know which parts perform what function, your powers of diagnosis will be much more powerful.
Radiator Inspection Service In Santa Rosa
Ensuring that your vehicle’s engine cooling system is in proper operating condition is extremely essential to engine life and performance. Operating at excessive temperatures can lead to premature engine wear. Your vehicle’s engine cooling system should be checked periodically, and a radiator coolant flush is also recommended to prohibit radiator corrosion. On Site Auto Repair will thoroughly drain and power flush the old coolant and particulates, and refill the cooling system with your vehicle manufacturer’s recommended coolant.
Our Santa Rosa Service Area – Directions to On Site Auto
Proudly serving drivers throughout Santa Rosa neighborhoods, from Railroad Square to Bennett Valley, and extending our trusted auto repair services to Petaluma, Sebastopol, Windsor, and all of Sonoma County.
Auto Mechanic Services We Offer in Sonoma, CA
We handle a wide range of repairs and maintenance, all performed at your location. Here's what we do most often for drivers in Sonoma and nearby areas like Glen Ellen, El Verano, Kenwood, Petaluma, and Santa Rosa.
Engine Diagnostics and Check Engine Light
That check engine light makes most people nervous — and honestly, it should. It's your car telling you something's off. We plug in an OBD-II scanner, pull the fault codes, and actually explain what they mean in plain English. No guesswork, no upselling you on repairs you don't need.
We diagnose the problem first, then give you a straight answer about what it will take to fix it.
Oil Change Service
We do full-synthetic and conventional oil changes at your home or workplace. We use the correct viscosity grade for your vehicle — 5W-30, 5W-20, 0W-20, or whatever your manufacturer specifies — and we replace the oil filter every time.
Honest truth: most people wait too long between oil changes. It's the cheapest maintenance you can do to extend the life of your engine. We make it easier by bringing it to you.
Brake Repair and Replacement
Worn brake pads squeak. Worn rotors grind. Soft pedals are a warning you shouldn't ignore. We inspect and replace brake pads, rotors, and calipers using both OEM-quality and aftermarket parts, depending on your preference and budget.
If you're hearing anything unusual from your brakes, don't wait. Brake jobs that get delayed usually end up costing more.
Battery Replacement and Testing
Dead batteries don't give much warning. We test your battery with a proper load tester — not just a voltage check — and if it's on its way out, we replace it with an AGM or standard lead-acid battery sized for your vehicle. We also check the alternator and charging system while we're at it, since a bad alternator kills new batteries fast.
Alternator and Starter Repair
If your car won't start or your battery keeps dying, the problem is often the alternator or starter. We test both, figure out which one is the culprit, and fix it on-site. This is exactly the kind of repair people think requires a shop — it usually doesn't.
AC and Heating Repair
Sonoma summers get warm. If your AC isn't blowing cold, we can recharge the refrigerant and check for leaks. If your heat isn't working in the colder months, we'll diagnose the issue and get it sorted. Comfort on the road matters, and we don't treat climate control as a low-priority service.
Scheduled Maintenance and Tune-Ups
Staying on top of scheduled maintenance is the single best way to avoid expensive repairs down the road. We handle:
- Spark plug replacement (iridium and platinum)
- Timing belt and serpentine belt inspection and replacement
- Air and cabin filter replacement
- Fuel system service and fuel injector cleaning
- Coolant system flush (HOAT and OAT compatible formulas)
- Transmission fluid flush and filter service
If you're not sure what your car is due for, we'll check your maintenance records or look it up by your vehicle's make, model, and mileage. We won't pad the list.
Tire Rotation and Inspection
Uneven tire wear is more than an aesthetics problem. It affects handling, fuel economy, and how long your tires last. We rotate your tires, check tread depth, inspect sidewalls, and check pressure. Simple service, done where you are.
Pre-Purchase Inspection
Thinking about buying a used car? Get it inspected before you commit. We'll look at what matters: brakes, belts, fluid conditions, undercarriage rust, suspension, and run a diagnostic scan for hidden fault codes. A $100-150 inspection can save you thousands on a bad purchase. We serve buyers all across the Sonoma Valley and into Napa County.
Roadside Assistance and Emergency Repairs
Stuck in Kenwood? Broken down near El Verano or out on Highway 12? If it's something we can fix on the spot, we will. Give us a call and we'll tell you honestly whether we can help or whether you need a tow.
Why Sonoma Drivers Choose On-Site Auto Repair
Most auto shops in and around Sonoma, CA do good work. The problem isn't the quality — it's the hassle. Drop the car off, wait for a call, figure out a ride home, go back and pick it up. That cycle eats your whole day.
We skip all of that.
Here's what you actually get when you book with us:
No tow truck needed. If your car starts (or even if it doesn't and you're local), we come to you. No dragging your car across town.
Flat-rate, upfront pricing. You know what it costs before we touch anything. No surprises when you get the bill.
Same-day appointments available. We know car problems don't schedule themselves. We do our best to get to you fast.
ASE Certified mechanic. Not a weekend hobbyist. A credentialed professional with real diagnostic tools.
California BAR Licensed. We're registered with the Bureau of Automotive Repair, which means we follow the rules and you have legal protections if something goes wrong. Most customers don't know to ask about this, but it matters.
Parts and labor warranty. Every repair is backed by a 12-month / 12,000-mile warranty. We stand behind our work.
We've been serving Sonoma, CA and the surrounding Sonoma County communities for years. Our Google reviews tell the story better than we can.
Ready to Book? Here's How It Works
Call or message us with your vehicle, location, and what's going on with your car.
Get a free estimate before we schedule anything.
Pick a time that works for you — at your home, office, or wherever the car is.
We show up, fix it, and you pay after the job is done.
That's it. No waiting rooms. No borrowed rides. No surprises on the bill.
On-Site Auto Repair — Sonoma, CA Serving Sonoma Valley, Glen Ellen, El Verano, Kenwood, Petaluma, Santa Rosa, and surrounding Sonoma County.
Things To Do In Santa Rosa, CA
From exploring the Charles M. Schulz Museum and Luther Burbank Home & Gardens to enjoying outdoor adventures at Spring Lake Regional Park and Annadel State Park, Santa Rosa offers endless opportunities for family fun, Wine Country experiences, and recreational activities that keep our community vibrant year-round.
Santa Rosa Transportation to On-Site Auto Repair
Conveniently located in the historic Railroad Square district with easy access from Highway 101, our auto repair shop is just minutes from downtown Santa Rosa, Santa Rosa Plaza, and all major neighborhoods, with nearby public transit options and walkable access to local shops and restaurants while your vehicle is being serviced.
Contact On-Site Auto Repair Today
Ready to experience honest, reliable auto repair in Santa Rosa?
Whether you’re dealing with a check engine light, need routine maintenance, or facing an unexpected breakdown, our ASE-certified mechanics are here to help. We serve drivers throughout Santa Rosa and Sonoma County with the same commitment to quality and honesty that has made us the area’s most trusted auto repair shop.
























