Car 801

Check-Engine Diagnostics, Done With Testing

A code names a system. Finding the actual failure takes driving the car and pulling live data, not reading a scanner and guessing.

The code stored in the computer is a starting point for diagnosis, not the diagnosis itself. The same code can be caused by several different failures upstream or downstream of the sensor that tripped it, and the only way to tell them apart is to test — checking live data while the car runs, checking wiring and connections, sometimes reproducing the condition that triggers the light in the first place.

A shop that skips that step and replaces the part the code seems to point at is running a parts-cannon repair: sometimes it happens to be right, and when it is not, you have paid for a part you did not need and the original problem is still there. The shops we match you with test first and can show you what the data actually said before asking you to approve a repair.

What this usually involves

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Other services

Get a Real Diagnosis Before a Real Bill

Tell us what the car is doing and we will match you with a shop that tests before it quotes.

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