Engine management light/fault code.

[AndyR]

Hi all, I have been preparing my Astra G for mot on Tuesday, and I've now got the engine symbol come up. I have had an obd reader on it, and it is saying that it has a misfire on number 3 cylinder. Could this be the coilpack or is there something else i should be looking at? I have changed all the spark plugs, and cleared all the fault codes, the light went out, but came back on after 3 miles.

Any advice in the right direction would be much appreciated, thanks in advance.

Andy  

[AndyR]

Forgot to add, that it is the Z16xe 16 valve ECOTECH engine. 

Thanks again.

Andy.