If you are going to do this yourself do it with the engine COLD. Coolant operate at over 100'C so it will burn you!
I think on that engine the sensor and thermostat are built as a single combined thermostat housing. The easiest way to find the Thermostat housing is to follow the large, black coolant pipe that is coming out of the top of the radiator. follow it back towards the engine and the other end of the hose should be attached to the thermostat housing.
On the 1.6 it is usually on the transmission end of the engine between the cylinder head and the air filter box housing which you will need to remove. Once you have removed the air filter box access to the housing is much easier.
I have attached a video link as a guide for the job. The car in the video may be different to yours but the 1.6 is a standard Citroen engine so it is fitted to lots of different models.
This engine uses the cartridge style filter and Not the screw on type. It is positioned on the front of the engine.
*NOTE* Do this with the engine oil COLD as engine oil can reach 250'F (120'C) and will cause burns!
Stand with your knees against the front grill and look down between the radiator and engine block. On the right side, (your right), on the engine next to the exhaust manifold there should be a large round, black plastic cap with a large bolt head shape on the top. This is usually a 27mm.
It is plastic so don't use too much force when unscrewing it and you might need to turn it a lot before it lifts off. The filter has rubber seal rings on it making it tight but it should just pull up and out.
When refitting install by HAND first to avoid stripping the threads. Tighten until it just becomes tight then STOP. The cap does not need to be too tight as it is on the Low pressure side of the oil system.
I've attached a photo as a guide.
Normally you just go to the dealership with the registration document and they give you the code. You will have to get the code from a site based on the serial number. Although many of these say 'FREE', expect to pay $12 to $18.
https://www.google.com/search?q=philips+radio+code+generator+free
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Do you mean its hard to turn when cornering? If so take a look at your power steering oil, it probably needs toping up. Although there are a number of other things it may be, but that is the first thing I would look at
It's possible that the filter is clogged or that there is a slight leak in one of the low pressure fuel lines that is allowing air into the system and causing it to lose prime.
This will depend on where the break is. If it is broken nearest the lever inside the car you could grab the cable with a pair of grips and pull it that way.
Do you need to open the bonnet to get the vehicle started? If the car runs and drives normally take it to a Good mechanic and they will have the tools to get it open.
If the cable has broken nearer the bonnet release at the front of the car it will be a lot more work.
If you use a torch and look behind the badge on the front grille you might be able to use a long flat head screwdriver to hook the release lever to 'pop' the bonnet but some car manufacturers fit a metal plate behind the grille to stop you doing this.
You could try SAFELY raising the front of the car and see if you can get to it from underneath.
Your LAST and more expensive method would be to damage the front grille and get to it that way.
I realise this is a late response, however Gosh no, do check the max towing weight of your model. we have a 2007 Grand Picasso 1.6 diesel and it is very light and while great as a vehicle not so much as a towing vehicle. I check the max tow weight as 1500kg braked
the 625 max loaded is around 1800kg so the car would be grossly overweight.
With ignition key off .. Hold right button down (2 buttons within the instrument cluster) Turn on ignition.. but not engine.. Watch for countdown till zero.. Release button.. All done.
