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Q: My engine light is on, why does my car hesitate sometimes when trying to accelerate or after I brake?

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My engine light came on a year ago after starting up my car on a normal day. Upon the light turning on my car began to shake like it's about to go out when I started it but did not. It kept shaking a few more times as I continued to drive it to possibly "warm it up" to get it driving, which after a few minutes of accelerating and trying to drive it, the car drove normally. Months later now, when accelerating the car does this hesitation action as if it's not making the right connections, then it goes after a few seconds. It does this now a few times a day the allows me to drive normally. I took it to autozone to have it ran by a computer and it diagnosed some possible misfires, spark plugs or injector fluid issues. Could it be my catalytic converter or my oxygen sensor?

My car has 160000 miles.
My car has an automatic transmission.

Misfires can be caused by a number of things. Poor fuel quality can cause misfires across all cylinders and possibly clog fuel injectors. Also, worn spark plugs can cause misfires as can the ignition coils that supply the spark plugs with the electricity to fire properly. Any of these will cause loss of power and economy. The oxygen sensor can also be a cause of poor performance but usually will set a fault code if the sensor has gone bad. Typically, a bad catalytic converter is not the "cause" of performance issues but is usually the "effect" of misfires and poor engine performance. If the catalytic converter is bad, something else (like misfires) made it go bad. Replacing the converter without addressing what made it go bad is not the route to take.

Since the cost of randomly replacing components can run into the hundreds, if not thousands of dollars, have a certified technician look into why the check engine light is on to isolate the exact cause. It will save you time and money.

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