So I'm still in the process of trying to fix up all the little problems on my '04. This time it's the rear parking sensors that's giving me a headache.
When I turn the park assist on, the system will show a "check park sonar" message and the rear center light flashes indicating that I have a broken park sensor here.


Here's the problem though: I've already replaced both (2) sensors in the middle of the rear bumper, and then the entire wiring harness (82163-50070) for the sensors themselves. Neither parts solved the issue.
The rest of the sensors on the car work perfectly fine. At this point I'm certain that the problem isn't as simple as just a bad sensor or a short in the wiring... Any ideas as to what could be causing this at all?

 

Try battery disconnect if not already done to reset the computers. Had to do one of mine with cheap sensor off ebay and worked fine. Why did you have to replace the wiring harness and maybe if have old one to put back on. Did all of the years use the same harness as maybe wires slightly different.

 

Already disconnected the battery multiple times prior to this with no results... My clock and seat settings and all that gets reset but the problem still seems to persist. The original wiring harness had a broken off connecter and the wires were affixed directly to the right rear sensor via some glue, so I thought I'd replace it thinking it could be the problem. Unfortunately it wasn't.

 

If you have techstream software it might be able to diagnose this problem. Also try switching sensors to see if problem moves and cleaning sonor computer connector. AI suggested this and can try....

• The "Click" Test: With the ignition on and parking sensors active, put your ear very close to each sensor (or use a mechanic's stethoscope). A working sensor will make a very faint, rapid clicking or ticking sound. If your new sensor is silent, it isn't getting power or signal.

 

It was the parking sensors themselves... I originally ruled them out since the "new" parts I ordered also presented the same issue when I installed them, but turns out those were broken as well!
I managed to find a repair manual online at https://ls430manual.pl and tested the resistance between the two prongs of the parking sensor. ~10kΩ should be the "correct" value, but the parts I ordered had ten times that amount of resistance! Returned them and bought actually working ones, now the system works like a charm. No more errors.

 

Where did you order the parking sensors from? Are they all the same (front/rear) or location specific? Differences between pre and post facelift or all the same? I don't get any errors, however they also don't seem to be working but I'm pretty sure that is from the bumper being painted and they painted over everything (including the chrome insert).

 

I ordered mine from a local web store (specific to my country), but I bet you can get plenty of results if you just search up on ebay.
The front and rear sensors are interchangeable, but note that the ones on the side are smaller in diameter compared to the ones in the center (this is true for both front and rear, you can tell if you take a close look at the sensors themselves). Pre and post facelift all use the same sensors so you're good there.

 

These are the sensor part numbers.
Rear centre two - 89341-50020-**, or 89341-50040-**, or 89341-50050-**
Rear outer two (1 each side) - 89341-50011-**

Front centre two - 89341-50020-**, or 89341-50040-**, or 89341-50050-**
Front outer four (2 each side) - 89341-50011-**

** is the 2 digit colour code if you want them colour matched.

I ordered mine from an Ebay supplier and got them all in black which is a close match to my dark blue LS.
All of the ones I replaced are still working fine, but a couple more of the OEM ones have failed so I will be replacing all of the OEM ones this time.

Yours will have been ruined by the paint. You cannot spray paint this type of sensor.

 

Agree you can't paint them. Knew this and got exact part # for my color and ordered on ebay and came a generic white even though it was for my # and not a bunch of numbers. If need exact color order from dealer.

 

Don't need to order from the dealer, just need to find the right place that sells them in OEM colors. The place I bought the parts from had multiple color options, and they aren't even OEM parts.

 

That's what I thought I did as this seller had different part numbers for different colors in other listings. Lexus parts will list the exact # for specific color but have to order from someone that does that. Where did you buy yours and get the exact color?