wife was coming home today and noticed at a stop car was hesitating
we have 170,000 kms
no engine light came on
but put the obd2 reader
and it found coedes po301 and po304 which is cylinder 1 misfire detected
and cylinder 4 misfire detected
cleared the codes and drove around and codes have not come back
but still will change spark plaus this weekend,,,is it a good idea to change the coils while im at it...
also trying to find on the internet but no luck..does the 2002 s40 come with 2 coils or 4 coils
also is ok to buy aftermarket coils compared to volvo coils at the dealship which is more money

thanks

 

The car has 2 coil.I would replace the the coils.When missfire code comes up in pairs like in your case it is most likely that the coil itself is at fault.One coil supplies the 1-4 cylinders the other one works on the 2-3. You have codes for the 1-4 but replace both coils.Yes OEM coil can be found at local stores you dont have to see the stealer.

 

well changed the plus with volvo plugs and also went with colis from volvo as well as it was $20 difference from aftermarket....noticed a couple of things when changed coil..not sure if it matters,,but the rubber boot of the coil had a tear...and notice the tubing for the wiring was falling apart..probably due to heat,,just bought new tubing....thinking if there is trouble again with hesitation,

 

check the coil wire harness that goes to the coils themselves.the s40 i worked on the wires just fell apart from the heat.there is a part from the dealer but,very pricey 175.00.