I've just acquired a 2004 MDX touring with under 100k miles. the CEL is on with the code thrown for S1B1 Knock sensor. I have the parts ordered to take care of that. but, the VTM-4 light comes on.. will this be on with a CEL just to say the system is disabled because of the CEL or do I need to hunt another issue? There's nothing I can see wrong, the car drives well shifts well, even with the sensor out it gets decent MPG. the VTM has NOT thrown any codes as far as I can read them anyways... any suggestions on what if anything this is?