Can i use the dash temp gauge sensor
 

...as the coolant temp sensor input on my megasquirt?

I have tried to do this already, and i get a crapton of sporadic behaviour. The gauge oscillates between 82'c, and a temperature figure about twice the engines actual coolant temp.

Car is a '90 1.6. I want to use this sensor for a spaceless reroute as this sensor is just before the thermostat. Search came up with nowt, im stumped. Ta.

Only if you disconnect it from both the gauge and body grounds.

Ive disconnected it from the gauge, it runs straight to the ECU and nothing else.

Its a one wire sensor though, so theres no seperating it from the engine ground. Dammit.

Thanks.

You could get a saturn 1.9L CLT sensor as it's 1/8NPT and fits right in place of that useless dash sensor.

See my thread

Ta for the tipoff deezums. Us UK lot never got any saturns but using your info i have found a 2 wire 1/8npt coolant temp sensor on ebay uk, with cal curve data. Hoping this fixes things.

These engines... Metric, BSP, and imperial threads all on one block. Pah.

So you know, I'm pretty sure the stock sensor is BSP but NPT is very close and should have no problems sealing. I ran an 1/8NPT tap down it, but I doubt even that is necessary.

Ah. 28 tpi for BSP and 27 for NPT aparantly. Im sure itll be fine, its only 8mm or so worth of thread...

Quick followup for the search.

1/8 NPT does not thread into 1/8 BSP, you will need to retap. Definatley not doable with the engine in the car/head on the block.

A 2 wire sensor is mandatory, the single wire sensors dont work.

Also make sure you get the resistance/temperature curves from the seller for any sensors bought.