I made this quick walkthrough because I've encountered a common issue you get with these cars where the locks form rust and either seize or the cable for the Volkswagen locks are broken and no longer catches. You can try greasing them, eventually you have to replace them.
This is the OEM part number 1K1823509E - used on my car (bought from a genuine VW STEALERSHIP @ around £38.
Alternatively you can check the current prices of these parts on eBay or Amazon to see if they work out better for you
My car is a MK5 with a 1KZ chassis (BKD Engine)
Just a note before I start, if your lock is stuck or the wire is broke, there are some suggested tips on the internet. If you are trying to get your bonnet closed, you can slam it down really hard. Sometimes this helps it catch. If you are trying to open the bonnet, you can get someone to pull up whilst pulling on the lever. If the lever or wire has snapped or come loose. Supposedly you can pop the front VW badge off the grille (rotate counter clockwise like a clock apparently) and pop the lock this way. I haven't actually tried it, but that's the research I found if you need to know how to open the VW bonnet when the lock is broekn
Anyway. The only two tools you will essentially need for the car. A T20 and T27 torx bit. Optional tools can be some insulation tape to hold the plastic guide in place as I found mine kept coming loose every now and then when refitting it to the car aswell as some zip ties and a flat-head screwdriver if you don’t have good pinching grip with your fingers.
The two T20 screws here and remove them from the car {yellow}, these are the screws just next to the headlights in this picture and then once they are removed from the car squeeze in the two plastic clips {red} can do one at a time and then remove the grill from the car.
It’s best to release the tension on the release handle for the bonnet lock before you start the assembly. Mine was always coming loose and I couldn’t work out why. I’m summising it is also because it doesn’t give enough flexibility to the new lock module after you have installed it into your car and it pushes it out of placement. Either this or it’s because the lock runner isn’t installed properly into the bonnet lock. This is how you release the tension on the pulley.
This is the layout of the T27 screws holding the lock in place on the car. There are two long ones holding the main part of the unit itself and a short one that holds the catch bar in place on the car. Make sure to fit these in the correct orientation when refitting your lock. This is a comparison to the lock placement in the above picture for future reference should it be required.
Once the screws for the lock have been removed from the car, it should be a case of extracting it. There is no real tension to it, you should be be able to remove it just by pulling on the normal piece of metal where the bonnet lock catches onto when you shut it after this it’s just a case of extracting it.
This is the plastic inside the guide, this must be fitted to the car otherwise it loses all tension in the bonnet release cable. It’s used to hold the cable the correct distance and so it doesn’t come loose from the car when fitting it
A common problem that I had when I was fitting the tensioner cable to the plastic guide was that it was slipping out and losing grip of the actual guide. This resulted in the cable losing tension and the lock not operating properly. I thought this may have been more due to not refitting the lock correctly but I didn’t want to take any chances. So I bodged the lock with some gaffer tape too. This was to reduce the chances of it coming off when I was trying to refit the lock back into the housing
This is how the wire should be connected to the car when the plastic guide is fitted to it. Or at least how I fitted it to my car, I’ve had no issues after fitting it to the car. Bonnet opens perfectly fine now
EDIT - Opens fine, but the problem with the VW is the bonnet is too light. So there is not enough weight to slam it shut if you drop it it just catches. I find if you lower it onto the first catch then give a quick shove it locks firmly
REFITTING
Refitting is a complete reversal of the removal procedure, before refitting the grill to the car, it is best to make sure the lock opens. You can manually force the lock closed on the car whilst the bonnet is open. When this has been done, make sure the lock tensioner ball has been reconnected again and then pull on the handle in the car. If the lock opens you should be OK for refitting the grill to the car.
To summarise the refitting procedure once the lock has been replaced on the car itself...