Frankenstein GEN 1 2002 prius code P3191 P0141 P0125 and power steering shake

blake9809 · Mar 28, 2023

ChapmanF said: ↑

The code is still an "insufficient temperature for closed loop fuel control" code. They are using the above detection condition to detect it.

When the engine is cold, it is hard to get the mixture rich enough. The fuel just condenses on the cold metal instead of mixing into the air. Old engines had a "choke" you would pull to close off the air supply to make the mixture rich enough for starting. Over the next half minute or so, as the engine warmed and the mixture got richer, you would back off the choke.

So your Gen 1 P0125 is saying "weird, been running 20 seconds, here I am driving down the road, and I still can't get the mixture rich enough. Am I warming up?"

So while we can think of ways the detection condition could be fooled by other issues, like a faulty sensor or bad injector, that doesn't mean we should rule out the code indicating the exact thing it's meant to indicate.
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ok so now that i somewhat understand what the code means and now my heads in a pretzel should i leave this alone or should i try to solve the issue causing the code? If so what should i try

ChapmanF · Mar 28, 2023

I'm strongly in favor of solving issues as they arise. Otherwise your car becomes this slowly growing heap of issues you've decided to ignore, and has warning lights always on so you can never tell if there's a new one, and it's halfway to jalopy status.

The troubleshooting steps for that code in the repair manual run to five pages.

Toyota Service Information and Where To Find It | PriusChat

blake9809 · Nov 28, 2023

ChapmanF said: ↑

The steering ECU is inside the cabin, behind the glove box, super easy to access. If you unplug it there, you spend zero time wriggling under the car and you don't have to worry about weatherproofing anything.

You kind of have your choice of unplugging the torque sensor (that plug has skinny wires) as the ECU won't send any motor signals if it's getting no torque input, or just unplugging the motor (that plug has fat wires) so it can't send any motor signals. Or just unplug everything from the steering ECU and put it on your bookshelf. Yes, all of that by definition puts the steering completely in limp mode, but then that's the idea.

It's possible the MFD might show what people keep calling the "PS MAIN EXCLAMATION POINT" screen (because it has three separate icons on it that can be gray or red, one for PS, one for the main battery, and a car with an exclamation point) and the PS icon will be red.

I'm pretty sure in my 2001 I had the steering ECU unplugged a few times, one way or another, and didn't get that screen, but I don't know if an '02 will react exactly the same way. You might find that your choice of exactly what to unplug influences whether you have to look at that screen or not.
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Its winter again and the electric steering is starting to shake at low speeds. I am going to disconnect the power steering computer today. Do i need to unplug all 4 connectors or just any single one?

ChapmanF · Nov 28, 2023

You kind of have your choice of unplugging the torque sensor (that plug has skinny wires) as the ECU won't send any motor signals if it's getting no torque input, or just unplugging the motor (that plug has fat wires) so it can't send any motor signals. Or just unplug everything from the steering ECU and put it on your bookshelf. Yes, all of that by definition puts the steering completely in limp mode, but then that's the idea.

blake9809 · Nov 28, 2023

ChapmanF said: ↑

You kind of have your choice of unplugging the torque sensor (that plug has skinny wires) as the ECU won't send any motor signals if it's getting no torque input, or just unplugging the motor (that plug has fat wires) so it can't send any motor signals. Or just unplug everything from the steering ECU and put it on your bookshelf. Yes, all of that by definition puts the steering completely in limp mode, but then that's the idea.
Click to expand...

ok got ya, i tried unplugging some wires today. Easy to find the module and also unplug the wires but got the annoying triangle and PS on screen. So i decided i am going to leave it plugged in for now but now i know what to do and how easy it is to unplug in case it gets a lot worse or wont stop.

Frankenstein GEN 1 2002 prius code P3191 P0141 P0125 and power steering shake

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Frankenstein GEN 1 2002 prius code P3191 P0141 P0125 and power steering shake

blake9809 Junior Member

ChapmanF Senior Member

blake9809 Junior Member

Attached Files:

Capture.JPG

ChapmanF Senior Member

blake9809 Junior Member