Service
Check engine light and diagnostics
Warning lights, rough running and problems that come and go. Diagnosis finds the cause before anyone quotes a repair.
When to stop driving
A flashing check engine light usually means a severe misfire that can overheat and damage the catalytic converter. Ease off, avoid hard acceleration and have it checked as soon as you can. If the light comes with overheating, a low oil pressure warning or a big loss of power, pull over where it's safe and turn the engine off.
A warning light, or a car that suddenly runs differently, means something has changed. Cars sold in the US since 1996 have an onboard diagnostic system (OBD-II) that stores trouble codes when it sees a problem. A code points to the system involved, not to a specific part, so good diagnosis means testing to confirm the cause before replacing anything.
What this service covers
Trouble codes and freeze-frame data
A scan tool reads the stored codes plus a snapshot of conditions when the fault happened, such as speed, engine temperature and load.
Live data and system tests
Watching sensors in real time and testing circuits, fuel delivery, ignition and airflow to confirm what the code suggests.
Leak and mechanical tests
Smoke tests for vacuum and evaporative (EVAP) leaks, and compression or leak-down tests when an engine problem is suspected.
Other warning lights
ABS, airbag (SRS), traction control, tire pressure (TPMS) and charging lights each have their own codes and tests.
Common signs you need it
- The check engine light is on, steady or flashing
- Rough idle, stalling, or hesitation when you accelerate
- Hard starting, or the engine cranks but won't start
- A sudden drop in fuel economy
- A smell of fuel, or exhaust that smells like rotten eggs
- Another warning light on the dash, such as ABS, airbag or battery
What to expect
Tell the story
When it happens, hot or cold, at what speed, and anything that changed recently. Details like these shorten diagnosis.
Scan and test
The technician reads codes and live data, then runs tests to pin down the cause.
Written estimate
You get the diagnosis and a written estimate for the repair before any repair work starts.
Repair and verify
After the repair, codes are cleared and the car is test-driven to confirm the fix.
How long it usually takes
Reading codes takes minutes. Finding the cause often takes an hour or more, and problems that come and go can take longer, because the car has to act up while it's being tested. Your written estimate will say what applies to your car.
Good to know
- A loose or worn gas cap can turn on the check engine light on many cars by setting an evaporative leak code. Tighten it until it clicks; the light may take a few days of normal driving to go out.
- Clearing codes or disconnecting the battery resets the car's readiness monitors. A smog check can be turned away until the car has been driven enough to rerun its self-tests.
- A free code read tells you the code, not the cause. It's a fine starting point, but the same code can come from several different problems.
California: written estimate first
Under California's Automotive Repair Act, a repair shop must give you a written estimate for parts and labor and get your authorization before starting work. If the job turns out to need more than the estimate, the shop has to get your OK before going over it. You can also ask for your replaced parts back when you authorize the work.
Check engine and diagnostics: common questions
Can I keep driving with the check engine light on?
If it's steady and the car drives normally, it's usually OK to drive for a short time, but have it checked soon so a small problem doesn't become a bigger one. If it's flashing, cut back on driving and get it checked right away. If you also see overheating, a low oil pressure warning or a big loss of power, stop where it's safe.
Why is there a charge for diagnosis?
Reading the code is quick. Testing to find which part or wire is actually at fault takes a technician's time and equipment, and it keeps you from paying for parts that don't fix the problem. In California, any diagnostic charge should be on your written estimate before work begins.
Will the light go off by itself?
Sometimes. If the condition that set the code goes away, many cars turn the light off after several trips without the fault. The code usually stays in memory, so it's still worth having it read.
Car acting up? Let's take a look.
Call (714) 555-0142 or send a request, and we'll find a time that works.