ok if a sensor goes bad does the check engine light automatically come on? and if so how do you know if the light isnt working?
94 f150 4x4 302

 

Eh, depends. The sensor has to fail to the point of being outside the expected range.

The challenge is that a sensor can be failed or failing, but the computer can adjust based on the incorrect feedback - so in some cases, until the computer reaches its limits of correction - won't get a light, but may notice decreased performance/economy.

The 'check engine' light does a self test on initial start-up - should see it then as part of normal starting procedure.

 

mine doesnt do that...
is there a way to hook it back up?

 

Suggest that the bulb is probably out - might try that first.

Whenever I have to pull the instrument panel for a failed bulb - I like to replace 'em all - figure if one is at the end of its lifespan, the rest aren't too far behind.