Which gauge to believe.

[BlueByYou]

I bought my cobra recently and it came with an already installed Autometer NV temp gauge. I assume it connects its sensor at the crossover fill plug as I see cables coming from a plug on top of fill plug.
I recently purchased and installed the Aeroforce Interceptor. Yesterday, I took the car out for a drive and there was a constant difference of about 10 -12 degrees between the two gauge. The Interceptor always read lower temps. If you're not familiar with the Interceptor, it only has ONE plug that goes directly to the ODB2 connector under the dash. That's it. No other wires to anywhere else.
Would it make sense to assume that each gauge has its sensor in different areas and therefore show different temps? If so, which one do you think would be more accurate? Thanks.

 

[blownfox]

There both likely correct it just depends on where the ECU is taking the temp from. The Interceptor is using what the ECU is seeing which will control fan kicking on and fan speed. The crossover fill plug should the hottest reading as that is coolant leaving the engine.

 

[01yellercobra]

There both likely correct it just depends on where the ECU is taking the temp from. The Interceptor is using what the ECU is seeing which will control fan kicking on and fan speed. The crossover fill plug should the hottest reading as that is coolant leaving the engine.

The sensor the ECU uses is in the crossover as well. It's on the leg going into the driver side head I believe. So they should be a lot closer than that.

OP, is the NV an electrical gauge with an electric sender? If so the sending unit might not have that great of a ground through the cap.

 

[BlueByYou]

This is the connector on the crossover.
You can see what looks like a secondary one below. Is that what you were referring too?

 

[SonicDTR]

I'd check the aftermarket sensor in boiling water to verify accuracy. But it would make sense for sensors in different locations to read slightly different.

 

[zredfire04]

I wouldn't worry about a 10 degree difference. They're probably both wrong by different amounts at different Temps.