Q: Check engine light flash with starting the car

asked by on June 17, 2016

I bought a used 2013 Chevy suburban. The check engine light keeps coming on and off. I brought it to one place and they said there is no problem. The next week when the light came back on I brought it back to the dealership I bought it from. They said there was a problem with an oxygen sensor replaced it. The next week apparently another oxygen sensor had to be replaced. Now the light doesn't flash when the car turns on and I was wondering if it's supposed to

The Check Engine light should illuminate when you turn the key on, and then go off after the engine is started. If it comes on anytime the engine is running, the vehicle’s computer has noticed an emissions related problem.

When the light comes on it also sets a Diagnostic Trouble Code (DTC) in the computer’s memory to assist the technician in diagnosis. The DTC does not tell a technician what part to repair or replace, but it does provide a starting point for what system to focus on in diagnosis. If your light comes on when you turn key on, and goes off after starting the engine, your Suburban is testing its systems and is ok with the results.

If the light persists, I would recommend having the vehicle checked. If you want to have this done, a technician from YourMechanic can conduct a thorough Check Engine Light diagnosis at your home or office and let you know how to proceed with a repair.

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