I plan to contact Innovate Motorsports about this issue, but I thought I would post here to see if anyone has any insight into this.

I recently installed an MTX-D coolant temperature gauge. When I first turned it on (with the included sensor connected), the gauge was reading 120F, which is the lower limit of its range. At the time, I was rewiring my engine, so I couldn't really test it out. Now the gauge reads 280F (upper limit) all the time, whether the engine is running or not. I tried disconnecting the sensor and powering up the gauge, to see if this would "reset" it. No such luck. As a side note, the gauge reads 120F with no sensor connected. I also checked continuity through the sensor at the plug, and I believe the resistance was only 1 Ohm, but in all fairness it could have been 1 kOhm. I need to repeat the test and double-check the unit of measure. I think the sensor should have significant resistance built in.

My assumption is that I ruined the sensor wire by twisting/bending it while installing. I had to unscrew it from and screw it back into the thermostat housing a couple times, and the cable is short, so there is not much slack. Does that sound plausible? Has anyone had experience with this?

 

Some senders require a separate ground wire. When not grounded they can automatically read the maximum.

 

Thanks for the reply. The sender has two wires attached (it is grounded). I think I'm just going to try ordering a new one. It's not much money.

 

Solution: I obtained a new sensor and compared its resistance with the one that I had installed. The new one measured 3.6 kOhm, and the old one measured only 1 Ohm. I plugged the new sensor into the gauge input, turned on the power, and the display showed a steady 120F. I then directed a heat gun at the sensor, and sure enough, the temperature started to rise. Thus, I was fairly sure my gauge and wiring were working properly. I removed the old sensor and noticed that the wiring was damaged where it exits the metal sensor body, which must have been the problem. I extended the wire of the newly installed sensor to give it more slack. It has been working ever since.