I just checked the speedo and it works fine, so thats not it. While under the car I noticed a plug dangling down. Its comes from the engine its coupled with the oxygen sensor, it looks to end before the O2 sensor, I cannot figure where it plugs into or what it is. My manual doesn't mention it. Does anyone know what this is. Again it runs with the O2 sensor but breaks out of the plastic cover and the o2 sensor continues. Puzzled!!