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

Is this for the manual gearbox?

Thanks for the reply! Yes I am sure it is u0303, but like you said it is not four wheel drive. possibly maybe the code reader I am using? It is more of an engine misfire so it sounds as though it could be p0303.

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

Okay, thanks, I presume a faulty maf sensor wouldn’t cause this ?

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.