P0340 code...now what

My CEL is on and according to Auto Zones code checker read a P0340 on my 2002 KIA Sedona with 160400 miles. It said Camshaft position sensor A circuit malfunction 1 or single sensor.

So what should I do now? Van is running as smooth as ever so not sure what I should do.

A crankshaft position sensor (CPS) basically feeds pulses to the computer when the engine is running because it is situated on the crank shaft. As it rotates, a pulse is generated. The code can be thrown when the computer knows it is supposed to see a pulse but doesn’t for a specific time.
If the CPS is dead, you won’t see pulses and the car won’t run. That’s clearly not the case with your vehicle.
You probably have an intermittent connection or an intermittent CPS. It may very well disappear when the computer detects that the pulses are coming frequently but it will store the code for diagnostics purposes. It may disappear but more likely it will just happen more frequently. You may even notice hickups in the way it drives, eventually.
It usually isn’t difficult to replace so won’t cost you an arm and a leg to fix, if you get it done. On some cars, they are right on top of the engine so you may even be able to do it yourself, if you’re half way handy with a wrench.

I believe its the cam shaft sensor which is different then crank which I did have to replace two years ago. Dealership wants $250 to replace and they are the overall best price of the three places I have checked with. Camshaft sensors come to about $135 of that for the parts alone.

You’re right. It is the camshaft sensor fault. I get dyslexic late at night. :slight_smile:
They do serve a similar function in that the computer needs to see it create pulses in a particular time frame.
Googling your error, this page comes up:

That link describes the CamShaft sensor to be on top of the engine. It may not be a difficult thing to do yourself. They are probably charging you an hour labor, which is not unreasonable.

I struggle putting gas in so always leave repairs to professionals and yes its an hour labor. So far all three places said that if the engine is operating fine that I have some time.

The light may very well go away for a while, when the computer decides it hasn’t happened for a while. It clearly is intermittent.
The problem with intermittent problems is that they could come back anytime, sometimes with a vengeance by becoming permanent, possibly leaving you stranded. I don’t think driving around with this light on will cause bigger problems but you won’t be able to pass an emission test. One bad thing is that, if your light is on with a relatively benign problem, it will mask serious problems when they occur: it isn’t like another problem makes that light turn on brighter. It will just still be on and you won’t know another problem occurred.
If I were you, I would fix it when able to.

The Camshaft Position Sensor fine tunes the injector pulse widths. When this sensor fails, the computer will go to default injector pulse width.

If you start to notice a drop in fuel mileage, replacing the CPS will fix that.


Indiana has no testing for anything. My plan is to put aside some money over the coming weeks to get repaired. Since I have AAA at least if it goes I have a tow service ready.

I would reset the CEL and see if the problem returns…

Interesting others here are telling me not to reset. Tried to get auto zone to do it when they read the code but they refused.

They won’t because they don’t want to be responsible for when something happens, you bring it to the shop and they say the codes have been erased that lead up to the problem. They are also betting that you’re going to get your car fixed there, which you should not on account of most of them pep boys being morons.

@Caddyman is right: it is worth a shot to see if it stays off. Maybe it was just a weird little glitch.
In the past, when problems are relatively benign (like forgetting to having tightened the gas cap), I’ve reset the light to see if it stays away.

Most shops won’t reset the light unless they’ve fixed it, though.
You could reset it yourself, if you know anyone that has an OBD2 reader. They are devices that plug into your service port, located just under the steering wheel, and allow you to read the PXXXX code and reset them.
HarborFreight has a cheap one: http://www.harborfreight.com/can-obdii-code-reader-with-multilingual-menu-98568.html
I’ve seen them for even cheaper, like 20 bucks or so.
Should you decide to go this route, be sure to note the PXXXX code and the time you read it so that, should the problem ever become a real problem, you have a record of it to help your mechanic fix it.

The Camshaft Position Sensor fine tunes the injector pulse widths.

@tester: How does the CPS fine tune the injector pulse width?
I understood the CPS pulse fed the ECM the cam/cylinder position, but that pulse width computation was derived from the other sensors (like throttle position, vacuum, engine rpm, O2, etc).

Is there something about the CPS that enables the ECM to compute pulse width?