please help prius dead will not start

What's your mileage? How's the condition of your 12v battery?

The knocking is very common with these cars. It's a beginning symptom of failing head gasket.

 

Measuring the 12v is the first level of diagnosis. Providing mileage and location helps as well. Most likely the 12v is too low and simply hooking up a charger for a few minutes may not be enough. Hopefully the high voltage battery is not excessively discharged due to far too many failed start attempts. That is rare. Using Dr Prius app or Car Scanner app with a bluetooth interface can read the high voltage.

Startup knocking that goes away quickly is typically a head gasket. How long this has been happening is essential to a better guess. A borescope can diagnose a head gasket unless its really bad and losing coolant and blowing white smoke. Then it is obvious without testing.

But we really don't know what you have or did because of a lack of details. A mechanic that charges $125 an hour will do all the legwork. Free advice requires more input from you.

https://bit.ly/ObdTwo

 

The two trouble codes you have listed only mean that the gasoline engine is producing less power than it ought to.

The good news is, there is nothing exotic or hybrid-specific about that. Figuring out why a gasoline engine is running poorly isn't much different in a Prius than in any car of the past century.

The bad news is, there are a lot of reasons to sort through for why a gasoline engine could be running poorly. In the days before exotic hybrid-specific stuff, the skills for figuring out why gasoline engines ran poorly could make up the lion's share of the skills auto mechanics needed to have.

So there might not be any quick answer from the internet, just a longer process of going through the possibilities.

 

If you're lucky it's just bad gas...

 

I assume you do not get Ready. Is that correct? Sometimes it takes several attempts after replacing the 12v battery. Does the engine attempt to spin on startup?

What is the 12v voltage now that you have tried to start it a few times since replacement?

Was a jump start from another battery or car attempted? My guess is you did not check the 125a fuse which blows on a reverse polarity jump. I would check voltages downstream of that fuse.

Since you changed plugs and tore apart the egr based on something, there is a real possibility some of the connectors were left unplugged or not completely engaged. We have also seen no start cases where fuses were checked and put back in the wrong slots, the brake light switch had failed or the inverter failed. If the orange plug on the hybrid battery was pulled, it may not be properly engaged.

Given you started with severe start up rattles, a blown head gasket was probably the initial issue but sometimes shotgun repairs can introduce a second issue such as bad connectors or blown fuse.

 

Inverter provides codes but you need a better scanner as described above. Several other questions are unanswered.

This means something basic, probably electrical, is being overlooked. Measuring power at various points in the above schematic is often key. Making an assumption that a particular test, measurement, connector or fuse is right because you looked at it before often turns out to be the bottom line troubleshooting error.

 

It is all in the details. Which 7.5 amp fuse? Why did it blow? If one blew there are likely others. You have so many sensors out I would guess another fuse is out, connectors are left off or a wiring harness is shorted. A lot of these stories end that way.

If it ran rough, with rattling and shaking for several minutes, it could mean it was because of a sensor. Keep looking and resist the maf parts cannon. First low cost aftermarket maf sensors are notoriously bad. Did you change that already? Only use oem but be ready for sticker shock.

I would not expect an illegal copy of Techstream to solve this faster than any other scanner that can read maf readings and the like. Techstream sold online by the bootleggers requires a windows registry hack and a special hardwired interface cable. Instructions on getting it going are sketchy. Even then there is a learning curve to use the software and many features are not available because you are instructed to keep it offline. Otherwise go back to post 4 above.

Sometimes it makes sense to let a dealer diagnose a car that has a multitude of problems. We still don't know what the 12v is now or when it is in Ready. We still may have fuse or connector problems. Never assume. Plus it could be a dead end if the engine has been ruined because of a longterm headgasket leak. Why not spend $150 at the dealer and find out rather than a similar amount for a maf and Techstream?

 

So you saved the $150 for a maf. That is excellent. We now know it goes to Ready. That alone proves most of the critical ecus are working and certainly the 12v at startup is good enough now.

Still don't know what the 12v reads in Ready. Still has lots of sensor codes I assume but maybe not. It is important to check off the issues as you go.

My money is on another fuse or fusible link which doesn't look like fuses and are sometimes overlooked. A charger properly used won't blow a fuse. A high amp charger installed backwards for a second blows several. Assuming the same fuse (which one?) is still good we know a little more.

Typically a tech would visually scan everything, read codes and then verify a series of voltages if no other obvious pathforward existed.

Spend the maf money at a dealer and you will know in an hour.