While driving on the interstate today my v50 with 2.4i began to misfire. CEL came on, info on dash read to slow down or downshift. Took it to auto zone and found codes P0303: cyl 3 misfire and P1800: vias S/V circuit. What does the P1800 code mean? I tried replacing spark plug and coil on cyl 3 with no improvement. only thing left is injector right? HELP!!!

 

It is possible that the injector is bad. Swap it out with another cylinder and then see if the misfire has moved

 

Upon further inspection the coil packs all have cracks under the boots. Guess Im replacing them all...

 

Yup that would cause the problem

 

Yeah, fairly common problem with coil-on-head setup; would have suggested swapping coils before injectors; latter almost never fail.

Any P1xxx (e.g. P1800) will be manufacturer (volvo) specific; you can ask the dealer what it is.. but first fix the coils, reset all the codes, and see if it comes back.