Part identification needed

Quite possibly; I believe the part is the engine oil pressure switch assembly, part number 83530-28020, sold in the U.S. as 83530-0E010, seen with part name code 83530 in the sixth illustration of catalog Figure 84-01, Switch & Relay & Computer. If you decide to replace it, see my previous posting about the procedure.

That’s not unusual for automotive wire harnesses.

The heated oxygen sensor is indeed in between the two catalytic converters, but the air/fuel ratio sensor is attached to the exhaust manifold, and there are several other sensors on the engine: camshaft and crankshaft position, knock, coolant temperature, and so on.

Just a tip: if you post a close-up photo of a part, it’s helpful to include a wider view, too, to orient viewers to where they’re looking. Not everyone here can recognize the left side of a 2ZR-FXE engine at a glance.

 

It’s definitely the oil pressure switch assembly.

In the listing for a 2ZR-FXE engine for sale from JDM of San Diego, for example, click the first image for a very clear photo of the left side of the engine. (The barcode label with the yellow paint is the same label seen in your wide-angle view.) Notice the oil pressure switch assembly threaded into its port on the rear of the block, with an electrical connector, gray plastic ring, and hexagonal head, just as in images of the 83530-28020 service part.