2004 prius to going over 30 mph

you probably need tech stream for the correct codes. is the inverter pump working? how old is the hybrid battery?

 

Wouldn't hurt to check if gas cap is on tight. It can trigger Check Engine Light, and might be tied into the EVAP warning?

 

Mine (06) wouldn't go over 30 when the tires on the front were 2" larger in circumference than the tires on the rear, the computer shut off the ice (internal combustion engine) so, check your air pressure, your tpms (tire pressure monitoring system) may not be working and one tire may have 12 pounds of pressure which would definitely tell the computers to shut down.

I was getting new tires and the tech broke a bead so only two got mounted until the next day, as I drove away I found that 30mph was the point that the ice turned off.

 

Out of curiosity when you say the oil was low?
How low is low?

Also you say you added a Fuel System Cleaner.
That in of itself shouldn't cause a problem, but my question is why?
Was the engine running rough or exhibiting symptoms that made you think a fuel system cleaner was necessary?

 

12v sounds weak, but wouldn't cause your symptom.
did it run okay after you added oil?

 

Yes, but is one of them VERY low on air?

 

hopefully not permanent damage. when does tech stream arrive?

 

oil is a funny thing. it is possible someone didn't fill it correctly. or by 200k, it is just burning more

without constant attention, it is difficult to be sure of anything

 

HOW TO CHECK INVERTER PUMP:

1) Prop open engine hood.
2) Open inverter reservoir (that opaque coolant container, next to the big square silver thing in the middle of the engine compartment).
3) Visually look inside the inverter reservoir. NOTE the calmness of the coolant inside this reservoir.
4) Make the car IG-ON or READY.
5) Visually look inside the inverter reservoir again. Do you see fluid movement? It should have a flow rate like a calm tranquil stream.
6) If it is quiet enough, you may even hear the inverter pump; its sounds like an aquarium air pump.
7) DO YOU SEE FLUID MOVEMENT in the inverter reservoir? Do you hear the inverter pump? If yes (fluid movement), Inverter pump is GOOD. If NO (fluid movement), inverter pump is bad and needs to be replaced.​

But, a failed inverter pump will produce different symptoms (ie A/C shutting off) and a different warning signs such as this ( ) on the MFD (Multi-Function Display) in the top left corner, when the inverter begins to overheat.

I will go out on a limb and say P0A80.

Original HV Battery (14 y/o).
Slow acceleration b/c the HV Battery is unable to provide the energy the electric motor needs. Car is operating on gas engine only. The Prius needs both (gas and electri motors) to run/accelerate properly.
​

OP can go to Autozone to get P0A80 confirmed, as their readers can pick this code up. But, their reader will miss many other codes. Techstream will be best to read codes and do work on the Prius; it is the official software written for Toyota/Lexus and used at both dealerships.

 

At 11V, the 12V batter is discharged. Recharge it w/ a smart AGM compatible charger.

You should find Post #5 and #8 useful
Is my inverter coolant pump slowly failing? | PriusChat

Post #5) How to apply a load.
Post #8) State of Charge chart, AGM compatible battery chargers.​

 

Very Low...really doesn't tell me much more than saying...low.
What I'm trying to get at...is was the oil BELOW the lowest fill line?
Are we possibly dealing with engine damage done by Oil Starvation?

Also...it's the height of optimism to hope adding oil and a fuel cleaner will fix codes, especially the red triangle of death. Doesn't cost much to do..and adding the oil was NECESSARY and needed. But once the light is illuminated and the codes thrown, you're probably past the point where doing those things FIX the problem.

Personally?
You can continue to try to self diagnose, but how much D.I.Y. are you willing to do with any diagnosis?
The quickest avenue to knowing, would be just to take it to a Hybrid repair facility.

I do say quickest, not cheapest, but you can spend a lot of time, and also a lot of money just trying to figure out something like this on your own.
Then if you're not prepared to do the repairs yourself? You end up at the repair shop anyway.

So sometimes not passing GO..and just going directly to the Service Department, I think can remove a lot of guessing, experimentation, and nickel and dime investments into vagueness.

Good Luck.

 

My guess is the hybrid battery is bad and the car is in limp mode.
12 volt is bad too and You have a high mileage motor that is eating lot of oil very common in a poorly maintained g2.