I've read about when individual sensors go bad, but I'm not sure if this is something different?

As soon as the car is turned on and goes through the self check, I get the alarm on the screen and in the gauge cluster that the parking sonar needs attention. I've included screenshots. Car is a 2004.

Anyone point me in the right direction?

 

Here's what the owner's manual says, does it help?

 

I checked the manual before posting. It isn't clear whether it's an individual sensor. If it is, which one? There are 2 in the rear center.

It's just not clear enough to move forward on a potential DIY fix.

Does anyone know if Techstream has any sort of test or diagnostic for parking sonar?

 

Next step is to pull the DTC from memory...

 

Excellent! Thanks! Is that done via Techstream or simple OBD scanner?

 

Usually you need Techstream to access Toyota/Lexus-specific DTCs. But a low-tech way to check your parking sensors is if you can still hear high-freqency sounds (or if you have access to a child), put an ear directly on the sensor while the parking system is activated and ignition is ON.

If the sensor is good, you will hear a high oscillation, regular, evenly spaced stream of bat-like clicking. If the sensor is bad, you'll hear nothing or an irregular sonar stream. Then you'll know which sensors are bad.

Strange that your system doesn't indicate the general area of the bad sensor. My 2002 nav screen shows whether it's 1 of the 3 in the front or 1 of the 2 corners.