While sitting at a light yesterday my 2005 hyundai accent died and would not restart. I towed it home and used my obd reader and it was throwing code p0340 which I understood was the camshaft position sensor. After waiting for the part to be delivered today I quickly changed it out and it changed nothing. Car still won't start, everything else seems to be fine and in working condition battery is fine starter is working great, fuel pump, compression is fine and I'm getting spark on my spark plugs. I cleared the trouble code before I tried starting the car and now it is back on. Not sure what to check next or what the actual probem could be? heard it could possibly be the crankshaft sensor? Please if anyone can help I could really use it.

 

I had the same trouble with my friends 2001 Accent. It may be the main engine relay. If you aren't measuring 12volts across the injector to ground then it's probably the relay. You can bypass the relay by putting a jumper fro the red to grey wire and see if it starts. Is so, they are $15 at Napa. The relay is under the drives dash mounted to the left wall.

 

ok does not seem to be the relay but thank you it was definitely worth checking. I had a friend come buy with a compression gauge and now it seem like cylinders 1 and 2 have no compression at all and 3 and 4 are reading 60 lbs. Any thought other than a damaged piston or piston ring?

 

Well it would seem to me that maybe your timing belt gave it up. The camshaft can not turn without a timing belt and so the valves on 1 & 2 are stuck open and the valves on 3 & 4 are closed. But this is just a guess as I am not a mechanic by any means. Anyway with no compression a timing belt would be the best case scenario cost wise although being a 2005 it shouldn't go that quickly.