Vauxhall/Opel Corsa, 1.2 LS 3dr, P reg, 97000. After traveling approximately 25 km the engine management light comes on. I used a Gunsons Fault Code Reader and thought the code was 0403 - EGR Valve, so I put a second hand on in. In actual fact the vehicle's fault code is 43 - Primary Signal Voltage High. What does this mean? How does it effect the running of the engine and its efficiency and how do I fix it?