Dandy. An open circuit, meaning a break in a wire to the sensor, will set a code for "high voltage". That's pretty common. It's less common to get one for "low voltage", but that one for sure can't be caused by the sensor. There are two wires going to a temperature sensor. One is its ground wire which will typically have 0.2 volts on it all the time. The other one is the signal wire that is fed with 5.0 volts from the computer. When the circuit is working properly, the sensor draws that voltage down to between 0.5 and 4.5 volts. That is the acceptable range for most 5.0 volt sensors. It's the voltage going outside that range that sets a fault code.
For a "voltage too low" code, it is almost always due to the signal wire being grounded. That will draw its voltage down to 0.0 volts which is outside the acceptable range. When that occurs right after some other service, it's usually due to pinching a wire accidentally. When it occurs on its own, the most common cause is a wiring harness has been sliding back and forth as the engine rocks, and the insulation has rubbed through, or it is draped over a metal bracket with sharp edges that cut into the wires.
You may be able to find this one on your own with just a digital voltmeter, but the readings will only be valid if the sensor remains plugged in. You can back-probe through the rubber seals where the wires go through into the connector. Find the wire with approximately 2.0 to 4.0 volts. The voltage will be lower as the temperature is higher. While watching the meter, tug and wiggle on the wiring harnesses. If you see the reading suddenly change, you're in the area that's causing the problem
Tuesday, December 2nd, 2014 AT 8:03 PM