Precision work. Master technicians. Fair quotes.
ASE Master Certified technicians, Maryland State Inspection on site, and the price explained before a single bolt comes off. No appointment needed: walk in during business hours and we take it from there.
One shop for the whole car
Foreign and domestic, from a state inspection to a transmission. The same technicians have been doing it in Rockville since 2008.
Maryland State Inspection
Authorized inspection station. Full safety inspection, results sent straight to the MVA, and a repair shop on site if something needs fixing first.
State inspection →Brakes & suspension
Pads, rotors, ABS service, shocks and struts. Squeal, grind or pulse in the pedal: many brake jobs can be done the same day; ask when you drop off.
Brakes & suspension →Wheel alignment
High-precision alignment plus tire mounting and balancing. Fixes the pull, the off-center wheel and the tires wearing on one edge.
Wheel alignment →Check engine & diagnostics
Drivability diagnostics with current scan tools. The light comes on, the code gets read, and you get the cause explained, not just a part swapped.
Diagnostics →A/C & cooling
Air conditioner recharge and repair, radiator and cooling-system work. Cold air in July and a temperature needle that stays where it belongs.
A/C & cooling →Everything else
Engine tune-ups, oil changes, transmission and clutch, EFI, radiators, power windows and locks: complete auto repair under one roof.
All services →Drop it off. Ride the Red Line. Pick it up on the way home.
The shop sits on N Stonestreet Avenue, one block from the Rockville station on Metro’s Red Line, the same stop the MARC Brunswick Line uses. Leave the car with us in the morning, walk to the platform, and pick it up in the evening. No second driver, no ride-share, no waiting room.
Heading into Bethesda or downtown DC? Every stop on the Shady Grove branch is a straight ride. Coming from the north end of the county? Shady Grove is one stop back.
- Shady Grove
- Rockville · Karnon
- Twinbrook
- North Bethesda
- Grosvenor–Strathmore
- Medical Center
- Bethesda
- Friendship Heights
- Tenleytown–AU
- Van Ness–UDC
- Cleveland Park
- Woodley Park
- Dupont Circle
- Farragut North
- Metro Center
Tell us the symptom, we’ll tell you the likely fix
A rough guide to what usually causes each one. The real answer comes from putting the car on the lift. Walk in and we will look.
Pick one to see what it usually means.
Usually: wheel alignment
A car that drifts when you loosen your grip, or a steering wheel that sits off-center on a straight road, is the classic sign the alignment is out, often after a pothole or a curb. Left alone it eats the edge of the tires. Worn tie-rod ends or a low tire can mimic it, which is why we check those first.
Usually: brake pads or rotors
A high squeal is often the wear indicator telling you the pads are near the end. A grind means metal on metal: stop driving on it if you can. A pulse in the pedal usually points at rotors. Often a same-day job, depending on parts.
Usually: a stored fault code. Read it, don’t guess
The light means the car’s computer has logged a fault. It can be as small as a loose gas cap or as serious as a misfire. A steady light means get it read soon; a flashing one means pull over and call. We read the code, confirm the cause, and explain it before anything is replaced.
Usually: low refrigerant, and the leak that caused it
Warm air from the vents is most often low refrigerant. A recharge fixes the symptom; finding where it escaped fixes the problem. We check pressures and look for the leak rather than topping it up every summer.
Usually: the cooling system. Treat it as urgent
A climbing temperature gauge, a sweet smell, or steam means coolant is going somewhere it should not: a leaking radiator, hose, water pump or thermostat. Do not push on; overheating turns a radiator job into an engine job. Call and we will tell you whether it is safe to drive the few blocks in.
Usually: ignition, fuel delivery or a sensor
Rough idle, stalling at lights or hard starting usually trace back to spark plugs and coils, a fuel or EFI issue, or a sensor feeding the computer bad numbers. This is what drivability diagnostics are for: it gets tested, not guessed at.
Usually: shocks, struts or a suspension bushing
A clunk over bumps, a bouncy ride after a dip, or the nose diving when you brake are the suspension talking. Worn shocks and struts also change how the car brakes and handles, so it is not just about comfort.
You need a Maryland State Inspection
A used car changing hands in Maryland needs a safety inspection certificate from a licensed station before the MVA will title and register it. We are one, and if the car needs work to pass, it can be done here and re-inspected without a second trip.
Usually: transmission or clutch service
Slipping, harsh shifts, a clutch that grabs high or a burning smell after a hill are early warnings. Caught early, a service or a clutch is a normal job; ignored, it becomes a rebuild. We work on automatics and manuals.
Usually: a window regulator, motor or lock actuator
A window that drops, grinds or stops halfway, or a lock that no longer answers the key fob, is a small electrical or mechanical part inside the door. Quick to diagnose; how fast it is fixed depends on the part.
Rated 4.6 on Google, and the reviews say the same three things
Fair price, honest explanation, done on time. Ninety-five Google reviews and counting. Here is what a few of them say, in the customers’ own words.
★★★★★“I have been coming to Karnon for 6 years now and he has worked on three different cars I’ve had over the years. I even moved to Arlington and still make the drive to Rockville when I need anything done.”
★★★★★“They did an excellent job on my Maryland state inspection and replaced the control arms in my car. The team was professional, friendly, and gave me a fair price. Never felt overcharged.”
★★★★★“I brought two cars to get inspected. First passed no problems. Second needed brakes. Karnon called first to tell me the price, which was reasonable, and did the job same day.”
What that light on the dash actually means
Tap a warning light. Red usually means stop soon; amber means get it looked at; blue is information. When in doubt, call and ask.
Check engine
Get it read soonThe engine computer has stored a fault. Causes range from a loose gas cap to a misfire or a failing sensor, and the same light covers all of them; the code is what tells you which.
If it is flashing, that is a misfire that can damage the catalytic converter: ease off, pull over safely, and call.
We read the code, confirm the cause, and quote before anything is replaced. Diagnostics →
Oil pressure
Stop the engineNot an “oil change due” reminder: this one means the engine is not getting oil pressure. Driving on it can destroy an engine in minutes.
Pull over, switch off, and check the level once it is safe. Low oil is the best case; a failing pump or sender is the other.
Call before you drive it anywhere. (301) 444-4410
Battery / charging
Head in todayWhile the engine is running, this light means the charging system is not keeping up: usually an alternator or belt, sometimes the battery itself. The car runs on what is left in the battery, then stops.
Turn off what you can (A/C, lights, radio) and come straight in while it still starts.
Charging-system test on site. Electrical & repair →
Coolant temperature
Pull overThe engine is overheating. Keep driving and a radiator or hose repair turns into a head gasket or a whole engine.
Switch off, let it cool, and do not open the radiator cap while it is hot. Blue on a cold morning simply means the engine is still warming up.
Radiator, hoses, thermostat, water pump: all on site. Cooling system →
Brake
Check it nowFirst, make sure the parking brake is fully released; that is the most common reason. If it stays on, the brake fluid may be low or there is a fault in the hydraulic system.
Low fluid often means worn pads or a leak. A soft or sinking pedal means stop driving and call.
Brake inspection and repair on site. Brakes →
ABS
Get it checkedThe anti-lock system has a fault and has switched itself off. Your normal brakes still work, but the wheels can lock in a hard stop or on a wet road. Often a wheel-speed sensor or wiring.
If the red brake light is on at the same time, treat it as urgent.
ABS diagnostics and repair. Brakes & ABS →
Tire pressure (TPMS)
Check the tiresOne or more tires is well below its recommended pressure. Cold snaps trigger it too. Top up to the pressure on the door-jamb sticker; if the light flashes for a minute or so and then stays on, the monitoring system itself has a fault, usually a sensor.
A tire that keeps dropping has a slow leak: a nail or a corroded rim seat.
Tire repair, mounting and balancing. Tires & alignment →
Airbag / SRS
Get it checkedThe supplemental restraint system has a fault, and the airbags may not deploy in a crash. The car drives normally, which is exactly why people ignore it. Often a seat sensor, a clock spring in the steering wheel, or a connector under a seat.
Scan and repair. Diagnostics →
Service due
Maintenance reminderThe maintenance schedule has come around: typically an oil change, filters, a rotation, or an inspection interval set by the manufacturer. Not an emergency, but the cheapest visit you will make all year if you keep to it.
Oil changes and scheduled maintenance, drop-off friendly. Maintenance →
Maryland State Inspection, with the repair shop attached
Buying or selling a used car in Maryland means a safety inspection certificate from a licensed station before the MVA will title it. Karnon Automotive is licensed by the Maryland State Police to perform them. The result goes to the MVA electronically, and if something fails, it can be repaired and re-inspected right here instead of at a second shop.
Not the emissions test: Maryland does that itself at its VEIP stations. But if a check-engine light is the reason you failed there, this is where it gets fixed.
Questions we get at the counter
Do I need an appointment?
No. Karnon Automotive is a walk-in shop: bring the car in during business hours and you will be helped. For a bigger job it helps to call (301) 444-4410 first so the bay is ready, but it is never required.
Do you do Maryland State Inspections?
Yes. Karnon Automotive is an authorized Maryland State Inspection station. The technician goes through the full safety inspection, the result is sent to the MVA electronically, and if anything fails it can be repaired and re-inspected in the same shop.
Do you do the emissions (VEIP) test?
No shop does. Maryland runs VEIP emissions tests only at its own state stations and self-service kiosks, such as the station in Derwood. What Karnon Automotive does is fix the reason a car failed: check-engine faults, emissions system repairs and drivability problems, so it passes when it goes back. Maryland's first VEIP retest is free.
Can I drop the car off before work?
Yes. The shop is one block from the Rockville Metro and MARC station on the Red Line, so you can leave the car in the morning, ride in, and pick it up on the way home.
Do you work on foreign and domestic cars?
Both. The shop has served all makes since 2008, with ASE Master Certified technicians and current computer diagnostics for the electronics in newer cars.
How does pricing work?
You get a fair quote up front, before any repair is done. The technician explains what was found and what it costs in plain language, in English, Spanish or French, and nothing goes ahead until you say so.
No form. No booking link. Just come in.
The fastest way to get help is to bring the car to the shop. If you would rather talk first, the phone is answered at the shop, not a call center.