What a diagnostic is, and when you need one
When a warning light comes on, the car has stored a fault code. Reading that code takes two minutes and is where a diagnosis starts. A code such as P0171 (system too lean) can come from a vacuum leak, a tired fuel pump, a dirty airflow sensor or an exhaust leak. Replacing the first part the code hints at is how people end up paying for parts they did not need.
Diagnostics is for any car that is doing something it should not: a light on the dash, a rough idle, a hesitation, a stall, a smell, a noise that comes and goes. It suits you if you want the cause found before money is spent on the fix.
Signs your car needs a diagnostic
- Check engine light on, steady or flashing
- Rough idle, hesitation or loss of power
- Hard starting or stalling
- Fuel economy has dropped for no clear reason
- ABS, airbag, traction or other warning lights
- A fault that comes and goes
How we track a fault down
- 01
You tell us what it is doing
When it happens, how often, hot or cold, and anything that changed recently. Those details save diagnostic time.
- 02
We read every module
Stored codes, pending codes and the freeze-frame data that shows what the engine was doing at the moment the fault set.
- 03
We test the suspect system
Live sensor data, smoke testing for leaks, fuel pressure, wiring and voltage checks, depending on where the codes point.
- 04
You get a plain answer
What failed, what it costs to fix and what can wait. Nothing is replaced until you say yes.
From a customer
Najeeb took the time to explain exactly what my car needed, answered every question without rushing me, and clearly knows his stuff.
Check engine light questions
Is it safe to drive with the check engine light on?
If the light is steady and the car feels normal, it is usually fine to drive to the shop. If it is flashing, the engine is misfiring and you should ease off and get it looked at right away, because raw fuel in the exhaust can damage the catalytic converter.
Can a loose gas cap really turn the light on?
Yes. The fuel system is sealed and the car tests it for leaks. A cap that is loose or has a worn seal fails that test. Tighten it until it clicks. The light can take a few days of normal driving to go out on its own.
A parts store read my code for free. Why do I need a diagnostic?
The code read is the first step. It names a circuit or a system. The diagnostic is the testing that finds which part in that system has actually failed, and whether something else caused it.
Will the light go off by itself?
Sometimes, if the fault was brief. The code stays stored in memory even after the light goes out, so we can still see what happened.
The light went off after the battery was disconnected. Is it fixed?
No. Disconnecting the battery erases the stored codes and the car's self-test results. If the fault is still there, the light comes back once the car has rerun its tests.
Where to find us
GTS Auto Repair is at 133 Manville Rd, Unit 32, Scarborough, ON M1L 4J7. We look after drivers from Scarborough and east Toronto.
