New purchase - now won't start !

Today collected a Puma Thunder, drove it home nearly 140 miles with no problems, now won't start. Using cheap Aldi OBD2 scanner, DTC code P0118 came up, oddly previous owner had said the temp gauge wasn't working, but it was all the way home.
As it was getting dark, I gave up for this evening, but tomorrow is going to be a steep learning curve using Forscan for the 1st. time, but 1st. I'll check the fuel pump and fuse, as that has apparently has happened twice before.

What is/isn't the car doing when you try to start it?

Does the fuel pump prime when you turn on the ignition?
Does the engine crank over?

The engine was cranking over OK, hadn't checked the fuel pump.
So this morning, it started 1st. time, with the rad fan on full speed, after a few mins, the fuel gauge suddenly moved and the engine revs went up to 1500 RPM and the rad fan was off. couldn't get the connector off the coolant temperature sensor, but gave it a good wiggle. Cleared the P0118 DTC, started engine and it ran fine, temperature gauge moved up normally. My conclusion is that it may have been a poor connection on the coolant temperature sensor. So need to get the connector off and clean the connectors. I assume there is a piece that need to be pushed in to release it.

Hi John, If you pull off the connector from the coolant temperature sensor , the fan should come on at full speed. Therefore it is possible that it wasn't making a connection at all.

If the fan comes on too early i.e. when the larger s shaped hose on the nearside of the rad isn't roasting hot to touch, then the sensor is likely to need to be replacing.

With regard to the non start issue, check that the pump buzzes for at least 2 seconds before you crank the engine, sounds as if the pump may be sticking , which is common on Pumas that have been left stood up for a long time.

Hi DOH, since Saturday morning the car has been starting normally (I'm aware of waiting a few seconds for the fuel pump, as I already have my other Puma).The previous owner said that the temp gauge wasn't working, but it is has worked fine for me.
I'm confused by the function of the coolant temp sensor, does it just tell the ECU the temp or does it feed the temp gauge as well ? I still have the P0118 error code even though the temp gauge appears to be working normally.
Thanks to this Forum I've managed to cure the sticking throttle by cleaning the throttle body inlet and cleaned the MAF while I was at it.

Have investigated further and have 4.8 volts coming to the sender plug. The sender appears to be O/C as I couldn't get a reading until the 2000 meg ohm scale, the engine has been stood for about 2 hours, so wasn't totally cold.
On my journey this morning the EML came on, but on my way back home it was off, the engine ran quite normally on both journeys.
I'm ordering a new sensor, as it seems most likely that's the problem.

Hi John I have replaced my coolant sensor twice as they do fail and they are a bit fragile. if the grey plastic has been rotated whilst in the head it can damage it & cause a poor connection.

I bought the following for mine last year & it worked fine.

https://www.ebay.co.uk/itm/113424755778

It has gone up a fair bit , as last year it was £9.50

Hi DOH, I was going to get one from the local factors, but finished up using eBay, a Delphi one, have double checked the part number so should be Ok. Have used Delphi parts before and always seem to be decent quality, unlike a lot of pattern part's. Apparently they should read about 3000 ohms, so being open circuit, convinced me it needs replacing.

UPDATE
Had a busy afternoon, after parts arrived this morning.
First priority was to stop the fuel leaking from the pump/sender unit, new seal seems to have cured it. The previous owner took the "easy" way when he changed the pump sender unit and cut an access hole beneath the rear seat, it made it a lot easier than dropping the fuel tank. In the future I want to fit the correct pump/sender unit, as the early type has been fitted and it only goes down to 3/4 full !
Then replaced the coolant temperature sensor, very straightforward, hardly any coolant lost. Then took the Thunder for a short 3 mile test drive, temp gauge worked normally, no high idle speed, no rad fan running at max speed. Checked for error codes with simple Aldi OBD2 tester and no codes found.
The old sensor was definitely open circuit, so taking it for a proper test tomorrow and hoping everything behaves normally.