Q: Car idling roughly and jerking, check engine light came on

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The car has been idling roughly and jerking randomly. I took it to a shop where I was told the spark plugs are worn. I had spark plugs replaced but it didn't solve the problem. I also had the fuel injectors cleaned but to no avail. Besides rough idling and jerking, the dashboard shows check engine light illuminated now as well. What should I do? What could be causing my car to run this badly? Thanks.

Quite a few items can cause a misfire condition in your vehicle. Usually worn spark plugs are the most common cause, so they are usually replaced first before diagnosis can proceed any further. Since yours have been replaced as well as the fuel injectors cleaned, that narrows down the possible causes to a vacuum leak, idle air control valve, oxygen sensor, or mass air flow sensor as these can all cause the misfire condition you have described. To have this looked at in person, a qualified technician, such as one from YourMechanic, will be able to diagnose rough idle and Check Engine Light to determine what repairs are appropriate.

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