Where is this massive oil leak coming from?!

Obviously I would check the drain plug bolt. Most likely the oil filter if it just suddenly started. After that it could be the low oil pressure sensor which sometimes blows through the sensor. If it was slow it could be one of those or a timing cover seep, very common.

I would check the oil filter first and get your under cover put back on to protect it.

 

The color looks more like it's an axle CV joint boot that's leaking lubricant. The joint by the transaxle looks totally dry. What about the joint at the front suspension? I'm just going by the first photo, the other two are messing my brain up. May not make sense with your other symptoms, like dripping on the transaxle and leaking after the engine is stopped, but weird things happen sometimes.

 

Just easier to view:





If I'm not mistaken, they're all at the left end, as you stand at front of engine bay? This zone is technically known as the "front" of the engine.

Timing chain tensioner, oil pressure sensor, or timing chain cover?

 

That sounds about right. Front of engine towards the firewall.
You'll need to hose down the area with degreaser and get a couple cans of brake cleaner too. Put the car up on ramps, clean it off to track down the leak. My money's on the timing cover where the head meets the lower engine block. Use the cans of brake clean to spot clean the questionable areas you couldn't get to with the water hose.

Hope this helps.....

 

No, not normally. The plastic bit of the sensor probably had a hair line defect or it was dropped before being installed. It just so happens that all those hot & cold cycles allowed the oil pressure to finally push through that small defect. Replace it and move on. DO NOT over-tighten or cross thread it - it's soft aluminum..

 

It has failed. You see the result. It is not an oil pressure transducer. It is just a switch which turns on a light when someone has no pressure. Usually because the engine burned all the oil. The engine will continue to run until it ruins itself.

 

Usu cause is 15W-50 oil. 27mm wrench. Chinese replacement will fail too no matter what oil used. U guys don't get over 75F there. Which oil did u use?

 

Torque info attached.

Where it calls for “Toyota Genuine Adhesive 1344, Three Bond 1344 or equivalent”, I’ve sub’d Permatex Threadlocker Blue, Insensitive (more effective in oily conditions) on PCV valve threads, seems similar efficacy.

 

Wow. Checked my atlas: all of Ireland (and England) is north of the 50'th latitude, apart from the extreme southern tip of Cornwall. For context, most of the Canada/US border is 49th latitude.