Welcome to On Site Auto Repair!
Auto Repair in Sonoma, CA — Honest, Reliable Service You Can Count On
Your car needs attention. You don’t have time to deal with a shop that keeps you guessing, pads the bill, or hands your car back with the same problem it came in with. At On-Site Auto Repair, we fix that. We’re a family-owned auto repair shop right here in Sonoma, CA, and we’ve built our reputation the old-fashioned way: honest work, fair prices, and no runaround.
Whether your check engine light just came on near Sonoma Plaza, your brakes are grinding on the Highway 12 corridor, or you’re simply overdue for an oil change, our ASE-certified technicians are ready to help. We work on sedans, SUVs, trucks, minivans, hybrids, and most domestic and foreign vehicles.
Why Sonoma Drivers Choose On-Site Auto Repair
Plenty of shops in Sonoma County will take your car. Fewer of them will give you a straight answer, a fair price, and actually fix the problem right the first time. Here’s what sets us apart.
ASE-Certified Technicians. Our mechanics hold ASE certifications. That means they’ve passed nationally recognized tests in their specialty areas and stay current with ongoing training. You’re not guessing about who’s working on your vehicle.
California BAR Licensed. We’re licensed by the California Bureau of Automotive Repair. That’s not just a formality. It means we follow state regulations on written estimates, authorizations, and your rights as a customer.
Transparent pricing. We give you a written estimate before any work starts. No surprise charges. No calling you mid-job with a bill that’s doubled. If we find something additional during the repair, we call you first.
Parts and labor warranty. We stand behind our work. Ask us about the specific warranty that applies to your repair.
OEM and quality aftermarket parts. We use OEM parts or quality aftermarket parts that meet or exceed manufacturer standards. We’ll tell you which option we’re recommending and why.
5-star rated on Google and Yelp. We’ve earned strong reviews from Sonoma Valley drivers because we treat every customer like a neighbor — because most of the time, you are.
Family-owned and local. We’re not a chain. We’re part of this community. When you bring your car to us, you’re talking to the people who actually do the work, not a customer service script.
Serving Sonoma, CA and the Surrounding Valley
We’re proud to be a local auto repair shop serving drivers throughout Sonoma Valley and Sonoma County. Our service area includes:
- Sonoma, CA (our home base)
- Boyes Hot Springs and El Verano
- Kenwood and Glen Ellen
- Petaluma, CA
- Napa, CA
- Santa Rosa, CA
Whether you commute along the Highway 12 corridor, run errands around Sonoma Plaza, or work near the Sonoma Raceway area, we’re the local shop that knows these roads, this climate, and the vehicles people around here drive.
Full-Service Auto Repair for Sonoma Valley Drivers
We handle everything from routine maintenance to complex engine and transmission work. You won’t need to drive to Santa Rosa or Napa for reliable car repair. We’re here in Sonoma Valley, and we cover the full range of services your vehicle needs to stay safe and running strong.
Engine Repair
Engine problems don’t fix themselves. A knocking engine, loss of power, or a check engine light that won’t go away are all signs something needs attention. Our technicians use a professional OBD-II scanner and diagnostic computer to pinpoint the exact issue before any work begins. You get a clear explanation of what’s wrong and a written estimate before we touch anything.
Brake Repair
Soft brakes, squealing, or a pulsating pedal mean it’s time to act. We inspect your entire braking system, replace brake pads and rotors when needed, and make sure everything is dialed in to manufacturer specs using a calibrated torque wrench. Most brake jobs are completed the same day.
Oil Change & Fluid Services
A regular oil change is the single best thing you can do for your engine. We use quality synthetic motor oil and replace filters — air, oil, and cabin — based on what your vehicle actually needs, not just a mileage chart. We also handle all fluid services: coolant, transmission fluid, brake fluid, and power steering.
Transmission Repair
Transmission problems are one of the more stressful things a car owner deals with. Slipping gears, delayed shifts, or a burning smell deserve attention right away. We diagnose transmission issues thoroughly and give you a straight answer about whether it needs a repair or a full replacement, with no pressure either way.
Suspension & Steering Repair
Potholes on Arnold Drive and the winding roads through Glen Ellen and Kenwood can wear out your suspension faster than you’d think. If your ride feels rough, your car pulls to one side, or your steering feels loose, bring it in. We use an alignment machine to restore proper geometry and make sure your tires wear evenly.
Electrical System & Battery Replacement
Modern vehicles have complex electrical systems. From a dead battery to a faulty alternator or a short in the wiring, we use a digital multimeter and vehicle-specific diagnostic software to track down electrical problems fast.
AC & Heating Repair
Sonoma summers get hot. A broken AC isn’t just uncomfortable, it’s a real problem during wine country’s peak season. We service and recharge AC systems, repair heating components, and make sure your cabin temperature is right before you leave the lot.
Radiator & Cooling System
Overheating is one of the fastest ways to cause serious engine damage. We inspect hoses, the thermostat, water pump, and the radiator itself. If any component is failing, we replace belts and hoses with quality parts and get your cooling system back in proper shape.
Tire Rotation & Wheel Alignment
Uneven wear, vibration at highway speed, or a car that drifts when you let go of the wheel are all signs your tires and alignment need attention. Regular tire rotations extend the life of your tires significantly. We do both, and we’ll show you the before-and-after alignment readings.
Smog Check & Certification
California’s smog requirements apply to most vehicles, and failing your smog test is a real headache. We’re a California BAR-licensed shop with a valid smog license. We run your vehicle through the test and, if it doesn’t pass, we diagnose the cause and fix it before re-testing.
Pre-Purchase Inspection
Thinking about buying a used car in Sonoma County? Don’t skip the pre-purchase inspection. Bring it to us before you commit. We run a full multi-point inspection and tell you exactly what you’re getting into, good or bad.
Diagnostic Services
Not sure what’s going on with your car? That’s fine. Bring it in and we’ll run a full diagnostic. You’ll leave knowing exactly what’s happening and what your options are.
Who We Serve
We work on most vehicle types and makes:
- Sedans and coupes
- SUVs and crossovers
- Trucks and pickups
- Minivans
- Hybrids
- Domestic and foreign vehicles
- Fleet vehicles for local businesses
If you’re in Sonoma, Boyes Hot Springs, El Verano, Kenwood, Glen Ellen, or nearby areas like Petaluma and Napa, we’re your local shop.
Ready to Book Your Auto Repair in Sonoma?
Don’t wait until a small problem becomes a big one. Whether your vehicle needs a quick oil change or a major repair, On-Site Auto Repair is ready to help.
Call us today to schedule your appointment or request a free estimate. We’ll give you a straight answer, a fair price, and work you can trust.
On-Site Auto Repair | Sonoma, CA | Serving Sonoma Valley and Sonoma County
Frequently Asked Questions
Our certified mechanics answer the most common car repair questions to help you stay informed and confident. Explore our FAQs for honest, expert advice trusted by CA drivers.
How do I know if my car actually needs what the mechanic recommends?
Honestly, this is the right question to ask. A trustworthy shop will always show you what they found, explain it in plain terms, and give you a written estimate before touching anything. At On-Site Auto Repair, we welcome questions. If we recommend a repair, we'll show you the part, explain what's failing, and tell you what happens if you wait. You decide. No pressure.
How long will my repair take?
It depends on what your car needs. Routine jobs like oil changes, brake pads, and tire rotations are often same-day. Engine diagnostics, transmission work, and parts that need to be ordered can take longer. We'll give you a realistic timeline upfront and call you if anything changes.
Do I need an appointment, or can I walk in?
We recommend calling ahead to make sure we can get you in at a time that works. We do our best to accommodate same-day requests for urgent issues. Drop-offs work well too if you can leave your vehicle with us.
What's included in a multi-point inspection?
A multi-point inspection covers the major systems of your vehicle: brakes, tires, suspension, fluid levels, belts, hoses, battery, lights, and more. It gives you a complete picture of your car's current condition so you can prioritize repairs and avoid surprises. We include this with many services at no extra charge.
Will you use my parts if I bring them in?
We can discuss this. The reason most shops prefer to source their own parts is that they can warranty both the part and the labor together. If you bring your own parts, we may not be able to offer the same warranty coverage on the repair. Give us a call and we'll be straightforward with you about how it works.
My check engine light is on, but my car seems fine. Do I still need to come in?
Yes, and sooner rather than later. A check engine light means your vehicle's computer has logged a fault code. Sometimes it's minor, like a loose gas cap. Other times it's an early warning of something that will get worse and more expensive if ignored. We can diagnose it quickly and tell you exactly what you're dealing with.
Do you work on hybrids and foreign vehicles?
Yes. We work on most domestic and foreign vehicles, including hybrids. If you're unsure whether we service your specific make and model, give us a call and we'll tell you right away.
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