Mercrusier 2008 6.2's are giving me a sensor fault - error:
BLK PSI CKT LO
This is from Rindas DiaCom software.

Engines are still under warrenty, but parts to the Bahamas are expensive, so I want to know I'm shipping the right part.

I am told this is the block water pressure sensor that is towards the back of the motor.

Here's the question: If the sensor is unplugged, should that fault stop, or is there a fault when the sensor is unplugged? Basically can I unplug the sensor to verify the condition?

Gardian also has the engine reduced to 90%.

unplugging the sensor will not change anything. If it is a constant beep, check you drive resevoir. If it is two beeps every minute or so, it is probably the water pressure sensor. It is located in the power steering cooler behind, and stbd side of the distributor.

Offshore,

Yes I thinks that's the one. I'm sure it's a bad sensor, so is there a way to deactivate it ( and restore to 100% power)while the new sensor is on the way- may take several weeks to get it.

I don't know of any way to by-pass it. That sensor is a very common problem. You might want to get a spare. You could remove it to see if there is any obstruction in the sensor port, sand, etc. I use a 1" deep socket.

Thanks I'll give that a shot.