P38A Temp gauge sensor confused

Guys wonder if your can help temp gauge on 4.6 hse only goes upto the blue mark no mater what temp the engine is running at, so looking in engine bay and all other v8s I've seen all have a single pole sensor on manifold for gauge, but on this p38 as you can see in the pic below it doesn't have one it has a bosh plug sensor on manifold which I believe to be for ecu, then a green one on the manifold outlet which I thought could be for sensor but have been informed that this is for ecu as well so now I'm confused can anyone shed any light?

Yours is a GEMS with two sensors. Motronic only have one that covers both functions. Green one is ECU sensor. Black one is gauge.

Cheers wammers I replaced the black one but gauge still sits in the blue any ideas for why the gauge doesn't work? I will replace the expensive green one as that's why it's prob running rich

wangie46 said:

Cheers wammers I replaced the black one but gauge still sits in the blue any ideas for why the gauge doesn't work? I will replace the expensive green one as that's why it's prob running rich

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Have you checked for voltage at connector with ignition on? Are you saying that gauge moves but stays in blue or does not move at all. If it moves and does not go above blue possible failed thermostat. But it's not often waxstats fail open. Get some diag on it before you start splashing cash about.