Q: Rough idle

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My Avalon was idling rough 2 weekends ago, then check engine light came on. Took it to dealership, they couldn't confirm the issue without a "complete teardown" but thought maybe there's a problem with a valve... (camshaft?) The car is running smooth now, and since Wednesday the check engine light isn't on anymore but I'd still like to have it looked at. (The timing belt was replaced about 4 years ago in case that matters.) It's a 2002 with 174,000 miles. Any guidance/thoughts you can provide are greatly appreciated! I'm not sure which YourMechanic service to select to get a quote and schedule an appointment.

My car has 174300 miles.
My car has an automatic transmission.

A rough idle may be caused by many different things such as low fuel pressure, low voltage to the fuel injectors, dirty fuel injectors, a vacuum leak, a faulty Oxygen sensor or a dirty or failing idle air control valve. Any of these possibilities relate to fuel delivery issues that will disrupt the normally balanced air/fuel mixture that would otherwise allow the motor to run smoothly. In the case of the valve issue that the dealership mentioned, this may have something to do with incorrect timing issues or potentially a faulty camshaft sensor or crankshaft position sensor. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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