Careful, don’t get caught in a wild goose chase: P0138 is Bank 1 (toward the firewall), Sensor 2 (Downstream sensor)

Anyway, do you mean there’s a bad exhaust smell, or something like an electrical fire smell?

If you have a basic OBD2 scan tool with a live-data feature, run the engine and check if your B1S2 voltages are higher than 1.2 volts for more than 10 seconds. If so, you’d proceed with an electric wiring/connector inspection & diagnosis.

If the voltage response isn’t stuck above 1.0 volts, start the diagnosis by assuming a bad sensor (Bank 1 Sensor 2).

Those are the usual symptoms of a battery that’s weak and/or discharged. The clicking is the starter solenoid unable to keep the starter engaged, due to the starter motor’s high demand for battery current.

Note that a discharged battery will suffer internal damage if it’s left in sub-freezing temperatures. If it’s got any hope at all, at this point, consider disconnecting it and letting it spend the night somewhere above 32 ^o F.

Check if there’s an auto parts store in your local area, that offers free battery testing/charging services.

I appreciate the reply Wishing the best of luck to you, going forward into the new year…!

Yep, the switch is easy to access. The main thing is to follow the right installation steps (like found in a Chilton manual) to align a new switch with the angle calibrated.

(Also, when removing the old one, to make sure not to damage the wide electrical connector’s plastic with reckless prying.)

Intermittent operation is common when those switches begin failing. If you were to crack it open, you’d see a really 19th-century-looking set of copper alloy electrical contacts. They’ll literally wear out to become uneven, over time.

Toyota used the same basic kind of switch across many years & many models, so for the diagnostics & remove/replace, some online videos would have helpful overviews.

The symptom of starting only in ‘Neutral’ will definitely mean a problem with the Neutral Safety Switch / Range Sensor, and/or the shift linkage connected to it.

Your dad’s theory is valid: There could be a slight linkage/mechanical hysteresis that’s causing the gear switch to register Drive gear only when approached from one direction (2—>D), but not when approached from the other (P—> D) direction.

If the mangled threads on the stud are the reason for replacement, have you first tried chasing the threads with a thread restorer kit, like this free loan-a-tool kit?

That would seem to be one of the two cooling fan switches, with the first one being at the bottom of the radiator.

Those plastic clips would be the “Christmas tree”-style plastic barbs. A clip pry tool can get around the center barb to wheedle out the clip without tearing it. The mouse will need another house.

Your friend of a friend is correct. That person does know cars more than the average person.

All of the other “some people” that you asked about it – well, they were talking out of their asses.

For now, the battery can be tested at an auto parts store that offers free battery testing/charging services.

Okay, so then the main question becomes: did the battery die because of a parasitic current draw? And might that cause a new battery to discharge while not in use? To answer that, even a basic $7 multimeter would be accurate enough for some basic diagnostics

The little locking bolt? https://parts.lakelandtoyota.com/showAssembly.aspx?ukey_assembly=486128&ukey_make=1060&ukey_model=15448&modelYear=1998&ukey_category=21646&ukey_driveLine=6739&ukey_trimLevel=18402

Generally if a dropped bolt doesn’t make the welcome sound of hitting the ground, a person would root around the subframe, suspension, and undercovers – especially in nooks & corners.

For installation, was there a problem of access, like a too-short wrench?

Hmm… Chances increase if that mechanic is already in the afterlife