2005 Kia Optima shutting off

My 2005 Kia Optima has 138,000 miles and cuts off after it has been running for a while. I’ve taken it to a Kia dealership and they replaced the Catalytic converter and an oxygen sensor but no help. I’ve taken it to a private shop and had the plugs replaced and the timing belt. Still no help. What could be the problem?

Does it cut off abruptly after running normally or does it run poorly just before cutting off? None of the items the dealer or private shop replaced are likely to cause it to cut off abruptly. Is the check engine light on?

Agreed with My 2 Cents; none of those things mentioned will cause a problem like this. Throwing expensive parts at a problem like this is really, really wild guessing; and bad guessing on your dime at that.

A wild guess might be the crankshaft position sensor as those can cause intermittent no-starts or random stalling after running. They may not illuminate the CEL or set any diagnostic trouble codes either.

It seems to happen after it has been driven for some time. Like and hour or more, then all of a sudden it cuts off while driving. The check engine light does not come on and it is not running hot.

Try replacing the crankshaft position sensor. These can fail intermittently when hot, without setting any diagnostic codes. Unfortunately this is almost impossible to diagnose. You just have to replace the part and hope it solves the problem. Fortunately it’s a relatively inexpensive job, unlike all the other stuff the dealership did.

I found on kia forum exact same problem and it was crank sensor.

I’ll have to agree with the three guys who suspect the crankshaft position sensor. It’s a good place to start and it’s cheap (relatively).

It just completely shuts off for no apparent reason and no advance warning and the engine stops and you coast to the side of the road? Then you can restart it right away, and it runs fine, like before? hmmm … It could be the ignition switch too. Especially if you have a lot of keys and other objects on your key chain, besides the advice above, suspect a faulty ignition switch. One thing you could try is to remove the key from your key chain and try driving with only that key in the ignition switch, and nothing else. If the problem goes away or become far less frequent, you can be pretty certain the ignition switch needs to be replaced.