Today’s engines are run by a computer that reads sensors and controls the ignition, fuel and emission systems. When the check engine light comes on, the computer has seen something it did not expect. Diagnosis finds out what that is, and any repair follows from the result.
Common reasons to call
- The check engine light is on, steady or flashing
- The engine runs rough, hesitates or stalls
- Poor acceleration or a drop in fuel economy
- The car is hard to start
- A failed emissions test or an emissions-related light
What we do
- Reading the engine computer for stored trouble codes
- Testing the sensors and circuits the codes point to
- Checking what the engine computer is commanding along with its condition and its sensors
- Explaining what was found
Diagnosis and repair are separate steps. This page does not list a diagnostic price. Ask what applies when you call.
Reading codes is the start of diagnosis, not the end
Scanning the engine computer gives us stored trouble codes. A code points to a system or circuit where the computer saw a reading it did not expect. It does not name the part to replace.
Testing the sensors and circuits behind the code is what finds the cause. Diagnosis and repair are separate steps, and any repair is your decision after we explain the result. This site does not list a diagnostic price, so ask about it when you call.
What to tell us when you call
You do not need to know what is wrong. Whatever you can share from this list helps us understand what to look at.
- Year, make and model of the vehicle
- Whether the check engine light is steady or flashing
- What the engine is doing: rough idle, hesitation, stalling, hard starting or poor acceleration
- When it happens: cold start, at idle, at highway speed
- Any other warning lights on the dash
- A failed emissions test, if that is why you are calling
How a visit works
- Call (325) 646-6206 and describe what is happening. There is no online booking or form.
- We will set a time to check the car. The first step is the evaluation, which finds the cause.
- Once the cause is known, we will explain it, and any repair is a separate decision for you.
- Prices and completion times are not listed online. Ask about both when you call, before you decide on any work.
How the engine computer works
A network of sensors and switches turns engine operating conditions into electrical signals. The computer reads those signals and, based on its programming, sends commands to the ignition, fuel and emission control systems.
Sensors involved
- Mass airflow sensor
- Throttle position sensor
- Manifold absolute pressure sensor
- Coolant temperature sensor
- Exhaust oxygen sensor
- Crankshaft position sensor
- Camshaft position sensor
Before you bring it in
A flashing check engine light is worth acting on quickly. Cut your driving short and call.
If you have your own code reader, note the codes, but bring the car in without clearing them so the stored information is still there. Your owner’s manual lists the routine maintenance your engine needs.
Check Engine Light & Engine Diagnostics questions
Is it safe to drive with the check engine light on?
A steady light usually means the car can be driven for a short time while you arrange a check. A flashing light often signals an engine misfire that can damage the catalytic converter, so cut your driving short and call as soon as you can.
Does a trouble code tell you which part to replace?
No. A code points to a circuit or system where the computer saw a reading it did not expect. The cause could be the sensor itself, its wiring or something else in the engine, so the code is a starting point for testing rather than a parts list.
What is the difference between diagnosis and repair?
Diagnosis finds the cause of the problem. Repair fixes it, and it is a separate step that comes after you know what is wrong. Ask about the diagnostic charge, if any, when you call.
Will tightening the gas cap turn the light off?
A loose or damaged gas cap can set an evaporative emissions code, so it is worth checking. Tighten it until it clicks. If the light is still on after a few days of driving, the car needs to be scanned.