ColinBarber

I'm pretty sure it isn't AGM - the fact that the OEM Panasonic battery has min/max fluid level markings implies it is a flooded battery of some kind. The OEM battery is 60 Ah (20 hours) so your Bosch has a very slight capacity advantage - which can only be a good thing 🙂

Yes on the front. The calliper is a 4 pot design, with 2 on each side which is unlike your single piston sliding calliper design that requires sliding pins that seize up. But the rears are all the sliding calliper design so will suffer the same issue if you don't do regular maintenance on them.

Sad you were forced into this Tony but seems like it has worked out okay for you.

No. It is a consumable item. It should be changed on a major service (it used to explicitly be part of the service but I've found dealers to be inconsistent with doing this), and a new battery should last you two years for when the next service is due but if it were to go flat before you needed a service then you would have to DIY or pay for it to be replaced.

Smart access is keyless entry - where you touch the door handle to lock/unlock. If you use this then you shouldn't be in any doubt if the vehicle is locked as you are standing right next to it when it locks so you hear the actuators. it's other people using it that is the problem - neighbours in the middle of the night in summer when I have windows open etc 😉 The UK law actually prevents the use of horns/sirens for stationary vehicles - it is inferred that this also includes alarm activation beeps which is why it isn't available when it might be in other countries. Most manufacturers don't allow this anymore because of the law. The beep on the tailgate is a safety warning and so it seems is allowed.

I assume you don’t have smart access? But you should still hear the doors lock though? Personally I dislike vehicles that make an unnecessary noise when locking/unlocking.

The opposite. E10 is less efficient than E5, all other things being equal because Ethanol has less energy density compared to gasoline as The Swedish Guy has stated. In addition, here in the UK E5 is only available as 97+ RON which itself is more efficient than 95 RON in our vehicles, so E10 actually has two strikes against it. Whether the extra efficiency you get with E5 overcomes the price premium depends on the vehicle and the difference in cost between the two which will vary considerable depending where you live in the UK. This thread isn't about the 450h+ but it is a good point - if you have a plug-in hybrid you want to be using your petrol at least every 6 months, and if you are going months not weeks without using it then E5 is certainly a better option.

Hybrids are designed for optimum fuel economy, hence the engines use thin oil (0W-20 in your case, but the latest models are down to 0W-8 now). But this comes at a cost of potentially higher wear and more noise - just moving from 0W-20 to 5W-30 isn't going to introduce intermittent tapping, if anything it should make the engine quieter - unless your oil ways are severely clogged and therefore you would be best to use a good quality engine flush to clear out any debris. 5W-30 is an approved grade for your engine: But as I've said previously, unless you know where the noise is coming from you may be debating something that is completely irrelevant to your issue.

Who is your insurer? LV?

Manifold leaks aren't always constant. They often occur on start up but once hot the metal expands and seals the crack, the IS-F can suffer this as an example. However it wouldn't typically come back again so is unlikely in this situation.

Seems they are just tarring all Lexus with the same brush - as far as I'm aware the CT isn't vulnerable to the CAN bus thefts of other Lexus models from roughly 2016 onwards, and I've not seem any reports here - only the old reports of CAT thefts which seems to have diminished over the last couple of years.

Only if wear and tear items need replacing - e.g. wiper blades/rubbers, bulbs, brake pad/discs, tyres etc. Anything that is covered by Relax and found during a service would be covered (provided you have Relax coverage to start with - i.e. you cannot have no warranty, take it for service and expect existing faults to be fixed, only once you have a clean bill of health would the 12 month warranty be issued).

The US has a different grading system for their petrol. Their premium is roughly the same as our standard, and Ultra is our premium. From the UK manual:

As has been stated above, get a mechanics stethoscope to try and locate. It could be a cracked exhaust manifold, injector, fuel pump, timing chain - not worth speculating until you can narrow down the area where it is coming from. https://www.screwfix.com/p/silverline-154006-mechanics-stethoscope/175fu

Regular 95 RON petrol. You can use premium if you want but it isn't a requirement.

Less is best - the grease is only performing a function on the moving surfaces. Spraying it all over the hinge body just creates a mess. I tend to apply, open/close the door a few times and then wipe off the excess.

I've not found a copy of the document to understand why - possibly it will react with the plastic, or owners get grease on the clothes, or maybe it attracts dirt and causes wear. To actively issue a statement to dealers not to do it must mean there is a reason. You would still apply it on the hinges.

This is only for smart entry, not pressing the fob buttons. After 5 days the vehicle reduces the frequency in which it transmits a signal to find a key to save battery life. It will always be listening to receive a signal sent from the key when a button is pressed.

FYI, Lexus no longer recommend grease on the door strap as per a TSB about 5 years ago: ABOLISHMENT OF GREASE APPLICATION TO DOOR CHECK

Do you have a dash cam installed? Some of them can interfere with the DAB signal.

Jeweller’s rouge, probably applied with a rotary polisher as it would take a long time by hand if it’s anything bigger than a single small scratch.

Dimensions:

It will be interesting to know what error code(s) you have. There are 4 sensors, the ABS sensor on each wheel hub which go to the ABS/VSC ECU which then generates a speed signal to the instrument cluster/speedo - I thought that losing one sensor doesn't stop the signal to the speedo.

Just buy one to save money and see if that clears some of the faults before getting a second one. I'd recommend getting Denso brand ones, non-OEM sensors have been known to still trigger errors.

start studying: https://www.lexus.co.uk/owners/about-my-lexus/manuals