just to clarify my previous input. The EEC is looking at the range of movement of each actuator (normally in %) and compares it to its own valid range in memory. If the range is different, or the EEC cannot determine the range the message is punched up. The EEC also compares both A and B channel inputs and operates on the input that is valid. With such an important engine system (VSV/VBV) I am suprised that an ENGINE CONTROL message has not appeared although it has been some time since I looked at the fault regime. maybe the harness needs tweeking
