I have a 2006 hyundai accent that has a check engine light on and ODB reads code PO340 camshaft sensor, i've changed sensor three times and code/check engine light comes back on, i've check all conections to ECM and plug from Sensor with no luck in clearing codes/check engine light. Any help on this topic would be appreciated...

 

When was the timing belt last changed? It's possible the cams are out of time by a tooth.