High Idle Speed

I have a 2000 Sonata 4 cylinder auto. It idles at 1500 rpm even when warm. Any suggestions as to the cause. Car has 48,ooo KMs and a new set of plugs and a new alternator recently. Thanks.

You need a trouble code scan. See if you have a code. It's either an intake leak, or perhaps the Idle speed actuator is bad.

That happened to me once and the problem was a leaking clutch fluid container...if your car is a manual that may be the problem.