My first thought is that you forgot to tighten something like a sway bar link, making loud sounds if they are worn or not tightened.

My other thought – Did you install new upper top mount bearings? If you put a shim or a washer in the wrong order it may cause a sound

If it only occurs on cylinder 4 which the p0304 code means, then you should check the ignition coils if you have it 🙂

Check this if you haven’t seen it https://mechanicbase.com/trouble-code/p0300/

Hello, what engine is it? Could be a crankshaft position sensor if it has difficulties starting warm. Otherwise, if the fuel pressure is a little bit too low I would guess fuel filter, fuel pump, etc. find more information here:

https://mechanicbase.com/engine/low-fuel-pressure-symptoms-causes/

Hi it all depends on how clogged it is. If it is just slightly clogged you can actually try to force a PDF filter regeneration with a diagnostic tool. Otherwise, there are special fluids your can clean it with but for this, you have to remove the filter.

Hi I can’t exactly understand the question, but if the front tires are leaning in the upper = negative camber, there is probably something wrong with your upper or under control arm bushings

If the starter is turning slowly, it definitely sounds like a power, ground issue or a faulty starter. It could be a ground issue between the engine-to-body or the car battery-to-body. Next time it happens, try to put a jumper cable between the engine-to-body or battery-to-body at some good ground points.

If the ground cables and power cables seem fine, I would take a look at the starter.

Basically, the AC system and the coolant system are two separate systems and have very little to do with each other. The only way I can imagine they did something is if they caused a leak by accident or forgot to plug in a wire for example. However, the chance seems very small so it’s very likely that it’s a coincidence.

The only way in my opinion to know if they did something is to let another workshop do the troubleshooting and after that see if it could be caused by them.

Because they are separate systems there is really nothing you do to check the AC system so it’s probably not something you will notice during the service either.

Continuing to drive with a broken AC system totally depends on what’s wrong with it. In most cases, there is nothing to worry about since the AC compressor will shut off and freely spin when the AC pressure is low. However, there is always a small chance that the AC compressor is broken and this could cause trouble if you drive with it so I would recommend a check as soon as possible!

Is it an electrical oil level gauge or when you check the dipstick? The oil level can differ a lot depending on if the engine is warm or cold also. The car needs to be standing on a flat surface with the engine off for at least 10 before you check the oil level to get a good measurement.