Screwy MTXL or???

[Roadrunner]

At this point I'm willing to give anything a go.
Odd that it's been perfectly fine for 7months and just going nuts now.
I think the solder join was only disturbed by my fiddling around disconnecting the sensor cable, it never dropped out etc before. So while it was a problem, I don't think it was causing an issue before yesterday. Or maybe it was causing a power issue all along and has fried the controller.

Maybe the SE is just getting jealous over the new ND purchase taking the main spot in the garage

[Roadrunner]

So solved the issue but not before some head scratching.
Replaced the sensor and everything returned to normal. For about 5 minutes before telling us it's idling at 19.x (clearly it's not).
So we swapped out the gauge unit for a new one. Still exibited the same behaviour.
Thought surely it can't be the extension cable. Soo pulled it out and pulled the new one through the fire wall and hey presto everything is working great!

Did a bit of searching and apparently there is circuitry in the plug end on this cable. Odd that this failed for whatever reason as the sensor and cable was less than 6 months old, but it's sorted now and it was dead easy to swap it all out on a hoist so I'm very happy.