Engine misfire, fault code U0303

Are you sure the code is not P0303? That code would indicate a misfire on cylinder three. That could be coil/wire/plug or internal engine issue. Easiest way to diagnose which would be to swap each part into a different cylinder one at a time and see which part causes the code in a different cylinder. Or just replace all the plugs with new and start there. Your choice.

The U0303 code would make sense if this was a four nwheel drive.

Hello,

These codes can be caused by a shaft speed sensor that is out of range. Here are the sensors locations. I would try the sensors first

Check out the diagrams (below).

Please let us know what you find. We are interested to see what it is.

Cheers, Ken

My bad, I did not see the transmission type. I would go with what Steve W. Has suggested.

If you are using a simple code reader most of those won't even read a U code, so I would bet it's supposed to be a P0303

It could but if it's a bad MAF I would expect a multiple random miss code (P0300) and a MAF code as well. You could try disconnecting the MAF and see if it uses substituted values to run better. Some will some won't.

Might want to have a shop pull the codes with a different scan tool and see what that shows. Would be real good if it displayed live data for the MAF flow rates and misfire counters.