ColinBarber

You will get warning beeps if the car isn't turned off. What is important is if you are just sitting in the car listening to the radio or programming a route in to the Sat Nav that you put the car into 'Ready' mode (foot on the brake and press the start button), even if that means the petrol engine will start and stop, and not just turn on accessory or ignition mode (pressing the button without your foot on the brake). If you aren't in ready mode then your battery will go flat very quickly.

There is very little you can do with Lexus hybrids in terms of tuning. Using sport mode will help with more battery assistance on partial throttle and a sharper throttle response but it isn't a fast car.

Wiring from the sensor goes directly to the engine ECU - so all within the engine bay

although humans need around 10 dB difference to perceive something twice as loud.

Then either fit a larger battery or reject/sell the vehicle and get something else, don't put your hopes into Lexus offering a retrofit upgrade. We all agree the situation is poor and that as described the vehicle isn't fit for purpose (as Lexus don't stipulate regular use in their sales information) but the workarounds suggested here are people trying to help improve the situation you are in, if you don't want people's help then please don't post here.

It’s a good question. Lexus vehicles had battery guard which gave you an alert if 12v battery was getting low. That Lexus link feature was removed from new vehicles a couple of years ago.

Yes, the OBD device does that. The 'tracker' is battery operated and in a low power state to just received a turn on signal that Tracker will emit if you report it stolen - only the permanently powered more expensive tracker devices report real-time location.

Number 3 Part code is 90919-05060. I normally recommend a fault is properly diagnosed rather than just swapping out parts but you can buy a 3rd party sensor on eBay for £8 - which would be the cheapest way to confirm if the sensor is at fault or not. You could then either keep that sensor or purchase a OE Denso one. Or you could swap intake and exhaust sensors over (3 and 4 above (same part for both)) to see if the fault changes or not.

Exhaust cam sensor fault.

The tracker is only activated when you report the vehicle as stolen.

Not sure what the video is trying to prove. The Yaris and LBX are full hybrids and don't need the battery to start the engine, therefore CCA rating is irrelevant. The Lexus uses a Japanese battery and the Toyota a European one because TMC locally source components. All three tested as you would expect for a battery in good condition. The issue with the batteries TMC are using in Toyota/Lexus hybrids is they are sized to reduce cost and weight to the minimum and the designers expect the vehicle to be in regular use. If you don't and you get to the point where the battery drain when the vehicle is switched off as more than is put back in when the vehicle is in use you will suffer a flat battery. As the batteries as so small, that may not take long. I also don't believe the designers have fully taken into account the extra drain the vehicles now experience for having always on internet connectivity and smart entry compared to a few years ago, so the problem has become worse over the years.

That OBD device will give you a warning that it has been unplugged. The tracker is a separate device.

Can't comment on 2 - don't know the cost difference in your country (and we never had the 350 in the UK). The carbon issue seems to be higher in the US, it is rare to see this issue in the UK that got to a stage where it impacted the running of the engine. Given the oil change interval in the US is less than the UK I can only assume it is related to people using poor quality oil in the US or there are emission differences with the engine. Do regular oil changes with fully synthetic oil and you shouldn't have too much of an issue. Certainly fit a catch can if you wish, it can only help. If you needed to have the engine cleaned, that would still probably be cheaper than selling the 250, buying a 350 and paying for more fuel the 350 would consume over your ownership.

It's the normal ripoff 😞

All sounds good but just remember that Dynax-UB is brown so you might get MOT comments that they cannot check for corrosion. Dynax-UC on brake lines, suspension springs etc. would avoid advisories.