Red Triangle keeps coming on intermittently

Try using special applications for your Techstream for computer/+a good scanner or a special Mini-VCI
There is an error in the hybrid system and your application does not see it.
Dr.Prius can try to find the error DTC

How long ago did you change the 12V battery?
What voltage does it hold before turning on the car in the morning?

 

Hello and welcome to PriusChat!

Generally the "master warning light" (Red Triangle of Death) is triggered by a fault in the hybrid drive system. Torque is a handy app, but it is very limited and can only "talk" to a couple of the 15 or so systems in a Gen2 Prius.

You need a more capable scantool to get codes and data from all systems. Here's a thread that reviews several scantool apps and devices.
(The Autel AP200 is a good choice for "basic" diagnostics)

https://priuschat.com/index.php?posts/3290690

Posted via the PriusChat mobile app.

 

I only know of two ways to get that triangle master warning without codes:

1) use a code reader that can't actually read all the codes out of a Prius- meaning there are codes, but your reader is blind to them.
2) low oil pressure.

Low oil pressure is not the same thing as low oil level. Low level cannot trigger any alarm in a Prius- though it can lead to low pressure, and low pressure will trigger the warning triangle alarm.

Levels are read by you when you pull the dipstick.

Pressure is read by a spring-loaded pressure switch- and there could possibly be a problem with the pressure, and it could just be a lousy switch.

 

get a free 12 volt load test at many auto parts stores

 

If I'm not mistaken, gen 4 did introduce an oil level sensor and an alarm for low oil level. Older Prius gens can only detect low pressure.

 

That sounds like a very discharged and/or bad battery. The MFD test isn't all that great because turning on the car to that extent will load the battery somewhat, which drops the voltage a little on a good battery, and potentially a lot on a bad battery. It should be more like 12.5V or higher on a good battery. The 14.1V when the car is running is coming from the inverter's 12V output, which is charging the 12V battery - it tells you the car thinks the 12V needs to be charged, and even that it needs to be charged a medium amount, but that's it.

Better to get a multimeter and measure the voltage at the jump point under the hood in the morning after leaving the hood unlatched (not open, just unlatched) over night. The point being that you don't want to unlock the doors or especially open the driver's door just to pull the hood release, as it wakes up the car's computers and the load changes the battery reading (temporarily). I usually use one of the unpainted bolts on the inverter for the ground test lead. Opening the unlatched hood doesn't trigger any activity. In theory some cars might have on open hood sensor that would trigger, but I don't think that option was installed in very many cars. It isn't in mine. A cheap multimeter is around $10 (at Harbor Freight) and a much better one can be had for around $50 (not at HF, although they sell some that cost that much). The leads on the cheap multimeters are often the first thing to go, which can lead to faulty readings.

You definitely need a better OBD2 reader, there should be a code to go with that triangle, and what you have cannot retrieve it.

How old is the inverter pump? They tend to go out at 60k miles (plus or minus a lot). If yours is working poorly or not at all the inverter will overheat and the triangle will light up. At least in the summer. In the winter you could certainly drive around in a suburban environment and never know that it is out, except maybe when driving on the highway. Anyway, with the car running take the lid off the coolant tank that sits next to the inverter (the skinny one with pink fluid, on the opposite side of the inverter from the fuse box) and see if the fluid is moving. NOT the radiator cap or radiator overflow tank - opening those on a warmed up car would be a really bad idea!