Looks like the fuel consumption is possibly better but difficult to be absolutely sure  because of all the different usage. Most time is on roads in High and looks like around 40 miles per UK gallon or 8+ miles (14k?) per litre. Running on 25" tyres.
Runs and starts well, idles down and accelerates fine with no misfiring or backfiring.
I am happy.

Ended up in a wheelchair in 2017 aged 66.... illness not stupidity.
Had to give up work, sell the Landrover 90 and the Harley 1200s, b*****.
A bit hilly round here so impossible to get out and about without someone else to push...mostly my wife. Tried out an electric "mobility scooter"...4mph on a path, 8mph on the road, huge, unstable, could not go up hills, not reliable in the wet or snow and a ****** nuisance to everyone else.
To get a decent "scooter" was more expensive than the CF450s. A 450s has proper suspension; proper brakes; proper lights; is stable; can go up hills; go off road; work in the wet and the snow; carry loads; tow a trailer; carry a passenger and is limited to 60mph not 8mph. Getting on required a little thought but otherwise excellent!
No brainer!
Thanks to Doctors, Nurses, Hospitals and family, still alive and able to walk about and the 450s is here to stay. Just waiting for the grandson to be old enough to come out with me.
A real lifesaver.

Have put a few more hours on since managing to sort the P0134 code and ending up replacing the original ECU.
1. Still no code!!!
2. Engine pick up from idle improved
3. Throttling back to idle much smoother
4. No random popping on over-run
5. Engine acceleration appears much smoother.

All of this is probably a bit subjective, but I feel like the whole engine management is "better". I wonder if the wire shorting problem started very soon after it was delivered to me or perhaps it is because the new ECU was manufactured and mapped in 2019 and not 2016 as was the one I replaced? I will never know.

I will check out the fuel consumption over a longer period and see if that has changed one way or the other.
Thanks once again for the help with this.

[orange]

In 2017 ended up in a wheelchair because of illness. Had to stop work as a dry-stone waller, sell my Landrover 90 and my Harley 1200s Sportster.
Pretty hilly round us hard work pushing me about so looked at getting an electric powered chair.
What a rip-off....most can't do hills, don't like the wet never mind snow and are unstable. An "all terrain"  version limited to 4mp or 8mph on the road!!!!
My new Cforce450s was less money, went off road, climbed any hill, wonderful in the snow or rain and is limited to 60mph...what's not to like?
Bright orange (so named "Zog" by my grandson after a storybook dragon. First thing when he arrives is to got and sit on the Quad); windscreen; heated grips; topbox; extra LED spots and rear lights; aluminium skid plates; and the usual excellent extras that come with the CF.
Two problems so far 1. Battery died after 4 years. 2. P0134 code now solved (read all about it on my thread..if you want).
Now walking again, within limits, but the Quad changed so much of my life for the better. The next plan....in 4 years take the grandson out as a passenger.

[SHORT HAD FRIED]

Yes, all it takes is time .....and money!

Rechecked everything including re-running the test on the O2 sensor and the spare I had bought when the code P0134 first showed up.
I was now convinced the SHORT HAD FRIED the ECU, well at least the bit that uses pin 24.

Thanks to Joe at Quadzilla UK (I am not being sponsored etc) I got a new one in the post yesterday and fitted it with great care.
THE CODE IS GONE!!!!!!!!
Quad starts, ticks over, accelerates, all functions seem fine
Longer run needed but am being hopeful.

The wires have a thick rubber pad between them and the frame. I have replaced the little plastic rivets that hold the ECU bracket with some decent bolts so it does not shake about....not a lot more to say except thanks for all the guidance and ideas.

I can honestly say I know an awful lot more about the electronic sytem, sensors etc etc. but checking the basic wiring was the way out of this.
Thanks to all.

[Check engine light flashing.]

Very frustrating morning....yet again.
1.Disconnected battery.
2.Unplugged ECU
3.Repaired insulation on wires.
4.Confirmed continuity from the 3 pins in the O2 connector with the correct pins on the ECU plug i.e. 24,21and 15.
5.Confirmed continuity with power supply that comes via fuel pump relay
6.Confirmed 5 amp O2 fuse intact
7.Confirmed heating circuit on O2 sensor
8.Reconnected O2 sensor
9.Reconnected ECU
10.Reconnected battery
11.Turned on ignition
12.Check engine light flashing.
13.Used my 3 pin socket on OBD plug to read codes (K line grounded) and confirmed was P0134 code
14.Started engine with OBD plug attached
15.Check engine light went off.
15.Engine started, ticked over, accelerated and returned to tick over no codes!!!
17.Switched off engine and unplugged OBD socket.
18.Ignition on >>>>>CODE IS BACK!!!
Repeat as above 11 to 18....... to infinity and beyond.

Yes, flashing remains so assume the fault remains....except if I leave the code reader plug on.

I am at a loss except I am now looking for a replacement ECU as that seems the only way to get these wheels back on/off the road.
Unless you out there know better?

[Double checked]

I'll give that a go, thought I had got it sorted,

Double checked wiring diagram (very very small in the book!)
1. Black/Orange hot wire from 5amp power supply switched on by the fuel pump relay (also to Idle control valve)
2. Red/Purple to ECU pin 15
3. Red/Blue to ECU pin 21 (links to TPS, T-MAP sensor, Coolant sensor)
4. Orange/White  ECU pin 24

As idling works fine, acceleration fine, starting fine assume ECU at pin 21 OK and power must be getting to Idle control valve so that circuit OK.

Have gone through the wiring and the attached photo shows what I found...
The wires from/to the O2 sensor are fixed to the frame with a zip tie.
When I removed it the damage to the wires was obvious.
The insulation on the wire to pin 2 on the sensor which connects it to pin 21 on the ECU and to the wire from pin 4 which connects to pin 24 on the ECU had shorted against the frame.
It is also possible that the black/orange may have done the same.
I checked the 5amp fuse for the sensor and it had NOT blown.
I checked and cleaned all the connectors including the ECU.
I made sure the wires were well separated BUT when the ignition is on and the engine running the fault code is still there.

As the ECU does not store codes I assume the problem still exists!!!

Is it now likely that the ECU is FRIED? It would seem likely

Thanks for that guidance. Apologies for the slow response but been away for a while and hope to get on with the search for the problem ASAP.
Been reading up on O2 sensors and checking through the wiring diagram that is in the hand book so now have a little more idea about your explanation of a possible source of the problem.
I will let you know how I get on

[does not store codes]

Having learned that 2016 Cforce 450s does not store codes I am about to start working through the problem which is causing the P0134 code;

1. Unplug and re-plug O2 sensor.  - no change
2. Connect new O2 sensor - no change - so assume a connection fault somewhere else
3. Checking through wiring diagram..........but where where next?

Guidance gratefully received

[ADDED]

The Cforce 450s owner's handbook that came with the machine listed the code P0134. However,  I had to go to this forum to find out how to get and read the flash intervals (by linking the K line to earth).

The dealer I originally bought it new from in 2017 is no longer with CF. According to the service guy who is still there they had to clear codes by requesting the loan of a PDA from the main agent.

As you say, the other possibility is that this is a faulty connection......once more stretching my technical skills to their limit (and beyond). Oh for a carburettor.

ADDED
OK
On reading through the handbook and maintenance manual I realised it does not say that the codes are stored
I had assumed that they were which sent me down a blind alley.

Grateful for that eyeopener now all I have to do is check the possible faults at connectors / pins etc.
Any guidance on where to start very gratefully received.
I guess this would possibly be a few hours search...could be expensive at the dealers.

Hi, flashing check engine light. Used the info from the excellent forum to read the code flashes.
The code is P0134 so suspected O2 sensor had died.
Replaced it but then how to clear codes and check?
450s has the 3 pin connector. Made up the link and attached OBD2 reader.
Yes can read codes but not clear them.
My original dealer is no more. The new local dealer did not recognise the 3pin and can only read OBD2 codes.
The technical stuff on the forum is great but stretches my technical skills.
Have a bluetooth link to my Android but the software does not recognise anything.
Quad seems to be running ok, not overheating,  ticks over, starts hot or cold....
Any solutions for a points, carburettor and old school brain?