2006 Prius shows P3193, but tank is full

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MountWeasel, Jan 5, 2025 at 12:55 PM.

  1. MountWeasel

    MountWeasel Junior Member

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    I have a 2006 (Gen 21) Prius that I'm trying to get running for my daughter. I've replaced the traction battery, 12V battery and catalytic converter. It will now run for about 20 seconds, then shuts off and triggers P3193, out of gas. I was pretty sure it wasn't out of gas, but I put gas in from a can until it ran out the fill spout, so I know it's full. I've cleared the codes and unhooked the battery, but the codes keep coming back. The combination meter also went blank, so I don't know how much gas the car thinks it has. I intend to replace the capacitor in the dash at first chance, but I don't really think this will fix it. Anyone know what else it could be?
     
  2. JC91006

    JC91006 Senior Member

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    How much gas do you think you were able to put in before it started to spill out?
     
  3. ChapmanF

    ChapmanF Senior Member

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    P3193 just means the same thing as P3191, only at the same time the combination meter didn't think there was much fuel in the tank.

    If you have recently unhooked the battery, the combination meter comes back with one flashing fuel segment for as long as it takes to figure out how much fuel you've really got, then it shows the real reading. If you get an engine no-start in that interval, it will be reported as P3193 instead of P3191. (Or, if the combination meter isn't working at all, same deal.)

    So, no need to sweat the amount of fuel if you know the tank is full. Just proceed as if you're diagnosing any ordinary P3191 no-start.
     
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  4. MountWeasel

    MountWeasel Junior Member

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    I had a 2 gallon can, and it only took about 1 gallon to fill it up completely until gas started to run out, so I know low gas was never the real issue.

    I'll pull the dash and solder in a new capacitor to get the combination meter working. My thought is that this should at least let me see how much fuel the car "thinks" is in the tank. Is this code set just by the fuel level in the tank? I've reset the code multiple times with my scanner, and it just comes back. It seems to run fine for the 20 seconds or so until the P3193 code gets set, so I don't suspect a true fuel or spark issue.
    The car has been sitting, and it was in a fender bender on the left front, so I had to replace a piece of the wiring harness with the abs sensor and inverter coolant reservoir connector, but the fuel tank is a long way away from the area where that damage occurred. Is there a resource that will tell us what is the code setting criteria? Is there a separate sensor that triggers the P3193 error, or is it just the same one that shows tank level on the combination meter?
    I guess it's time to print out the wiring diagrams and look at the relevant signal(s) with a meter.
    I haven't seen this issue before, so any direction would definitely be appreciated.
     
  5. Brian1954

    Brian1954 Senior Member

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    Read post #3.
     
  6. MountWeasel

    MountWeasel Junior Member

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    Thanks for the responses, and I don’t want to appear obstinate, but I’ve read post #3, and am having a little trouble understanding how it applies in my case, since even an hour after I reset power, the same p3193 reappears after I clear the codes. Since the engine starts and runs perfectly for around 30 seconds until the p3193 code comes back, I’m not sure how to proceed to troubleshoot a p3191 no start code. Any thoughts on that would be appreciated. If I understand correctly, after power is restored, the fuel gauge has one flashing segment until the computer figures out what the fuel level actually is, then it displays correctly. With a blank combination meter, I don’t really know what the reported fuel level is. Is it possible that a faulty tank level sensor (or wiring) is erroneously reporting out of gas, causing the recurring condition that I’m seeing? My hope is that if I fix the combination meter capacitor, I can at least tell what the reported tank level is, and get some diagnostic direction that way. Am I way off track here? Again, I’m incredibly grateful for the cumulative experience and knowledge of the Priuschat community, and will gladly perform any suggested tests to diagnostics this issue. This is the fourth Prius in my family, and I admire the job that Toyota did designing this remarkable car.
     
  7. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    From Post #3

    . (Or, if the combination meter isn't working at all, same deal.)
    Since you say the combination meter is blank, that is likely your issue. Fix or replace it.
     
  8. ChapmanF

    ChapmanF Senior Member

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    "The engine starts and runs perfectly for mumble seconds, so why do I have this no-start code?" is a very classic PriusChat question. Most cars crank the engine with a wheezy little 12-volt starter motor, and the engine sounds completely different when it really starts. Prius cranks the engine with one of the multi-kilowatt motors also used to drive the car, and it cranks over at the same speed as a started engine right away. It's very hard to tell by the sound whether it ever started or not. If the ECM is saying it didn't, it didn't.
     
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  9. Brian1954

    Brian1954 Senior Member

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    I think you have two separate problems.
    1. The combination meter is not working
    2. The engine is not starting , code P3191.

    Is one problem causing or affecting the other problem? I do not think so. They are two separate problems that can be fixed separately.

    You already know that the potential fix for the combination meter is to replace one or more capacitors. You can try to fix the combination meter first, or you can try to get the car started first. It does not matter which one you fix first.

    The engine not starting is the more difficult problem to fix, in my opinion. Even though you think the engine is running for 20 seconds, it is not running. What you are hearing is one of the motors in the tranaxle spinning the engine and trying to start the engine. Every time you try to start the engine, electrical energy is being used from the hybrid battery. If you continue trying to start the engine, eventually, there will not be enough energy left in the battery to start the engine. Then you will have another problem to fix.

    The first thing I would do is use a good Prius capable scan tool (like the Autel AP200) to check for trouble codes. Look at post #37 of this thread for different scan tools. https://priuschat.com/index.php?posts/3290690

    The engine needs the following to create combustion in the cylinder:
    1. Air
    2. Fuel
    3. Spark
    4. Compression

    Try to find the step by step Toyota service manual for code P3191 by doing a search on the web.

    The P3191 code is not an easy thing to diagnose. It can be caused by many different things like a bad fuel pump, problem with the throttle body, a vacuum hose that has come off, the MAF sensor, etc.

    Can you provide more information about the history of the Prius? How long have you owned the car? How long has the car been sitting? When was the last time the car was working properly? Etc.....

    Good luck.

    Edit: the Toyota service manual link: https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://attachments.priuschat.com/attachment-files/2018/05/146976_2006_Prius_RM_-_DTC_P3191_Inspect_Proc.pdf&ved=2ahUKEwit9rSl8N-KAxXAj4kEHV7AODwQFnoECCUQAQ&usg=AOvVaw27cggb6PKlSD5FH86n8SQZ
    The link appears to be only 1/2 of what you need.
     
    #9 Brian1954, Jan 5, 2025 at 6:28 PM
    Last edited: Jan 5, 2025 at 9:40 PM
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  10. MountWeasel

    MountWeasel Junior Member

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    Au Contraire, Mon Freres, I can state definitely, positively and unequivocally that the ICE is starting and running 20 seconds or so until the p3193 code is set. How do I know? I installed a new catalytic converter to replace one that was stolen, and I still have a small exhaust leak, so there is absolutely no doubt whatsoever if and when the ICE is running. Also, I’ve had three other gen 2’s with bad combination meter capacitors, and they all ran quite happily with blank combination meters and without setting the p3193 code (until they actually ran out of gas), so I’m confident a bad combination meter isn’t setting the code.
    I’ve successfully fixed all three bad mfm’s, and I even bought a dozen of the correct electrolytic caps off amazon so I wouldn’t have to scrounge them from my son’s old cassette players, so I feel pretty confident that I can fix it. This brings us back to p3193, out of gas.
    1. I know the engine is starting and running, so to me, there’s no need to further chase down that rabbit hole.
    2. When the engine shuts off, it sets code P3193, not p3191, not even once, no matter how long it’s been since the 12 V power has been on.
    3. I’ve got gas running out the filler, so I know the tank is full.
    Therefore, to me, the condition which kills the ICE also sets P3193, and it’s not because the tank is or ever was empty, or because the ICE isn’t starting.
    My working theory is that the computer is getting a false signal indicating an empty tank, which shuts down the ICE after 30 seconds, and sets P3193 code. I can probably find a parameter indicating fuel level using my Autel bi-directional code reader, but I know the mfm capacitor needs to be replaced anyways, so I think I’ll just do that first. If I’m right, then the fuel gauge will show empty no matter the level of the tank, and I’ll need to then replace the sending unit, or fix a wiring problem.

    history of the car:
    It has about 75k miles, and I bought it for my 16 yr old daughter non-running for a pretty low price. Previous owner said his mechanic had replaced the traction battery, 12 v battery, left fender, and dash, but still couldn’t get it running. (And the mfm was still intermittent). So it sat in a church parking lot for about a year until he was finally told to do something with it. By then, the cat had been stolen, one back door window was broken out, and of course, both batteries had gone bad from lack of charging.
    I bought it off Facebook, replaced both batteries, the cat, and the back window, and I’m trying to get it running before the traction battery again fails from lack of use.
    That’s it. I’ve got a clean 75k Prius that only runs for 30 seconds before setting the p3193 code, and the intermittent multi function meter is now mostly off, so I don’t know what fuel level is being reported to the computer, but I suspect it’s mostly 0.
    Back to my original question: what is the code setting criteria for P3193? Is it low analog fuel level signal, low fuel pump pressure, a discrete low level switch, or something else entirely?
    Again, any and all suggestions are really appreciated. In my 10 years or so of owning gen2 prii, I haven’t come across this particular symptom, so I’m scratching my head a bit.
     
    #10 MountWeasel, Jan 5, 2025 at 7:13 PM
    Last edited by a moderator: Jan 6, 2025 at 3:01 AM
  11. ChapmanF

    ChapmanF Senior Member

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    It's the AND of two things:

    • The criteria for P3190 / P3191 have been satisfied, and
    • The combination meter's empty/not-empty signal to the ECM hasn't said not-empty.
     
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  12. MountWeasel

    MountWeasel Junior Member

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    Humble pie. Ok, had to consider it a bit to be convinced, but now that I think about it, maybe the ICE only sounds like it’s running, and the exhausty noises are just uncombusted gases being pumped through the cylinders at 1100 RPM running speed, like a giant air compressor. I’ll tackle it again when I get back to the states next week. Thanks for making me reconsider the facts in front of me. I’ll keep you posted.
     
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  13. Brian1954

    Brian1954 Senior Member

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    I edited my post #9. Look at the link I provided at the end and download the PDF, and you can read about it yourself. That PDF is only 1/2 of what you need to troubleshoot the trouble code. You are going down a rabbit hole looking at the fuel level signal.

    Note: I did not see posts #12 & #13 when I created this post. (I had not reloaded the old web page)
     
    #13 Brian1954, Jan 5, 2025 at 9:33 PM
    Last edited: Jan 5, 2025 at 9:53 PM
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  14. dolj

    dolj Senior Member

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    I just want to highlight a crucial piece of info given in post #9:
    Once the HV battery gets below ~210 V the battery is below ~40% SoC. I don't know what the minimum voltage the car will allow you to crank the engine. I have read posts that suggest that that voltage might be 198 V to 200 V. So, it might be a good idea to have a method of charging the HV battery so that you can keep the voltage above 210 V.
     
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  15. MountWeasel

    MountWeasel Junior Member

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    Think I’ll try something new, stop explaining why I think I’m right, and start listening to the voices of experience.
    So, what can I get to keep the traction battery charged while I figure out why the ice isn’t starting?
     
  16. dolj

    dolj Senior Member

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  17. mr_guy_mann

    mr_guy_mann Senior Member

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    The CM receives the fuel level signal, processes it and sends the data out on the network bus to the ECM. Until the CM is fixed, the ECM can only think that the tank is empty (nothing to tell it otherwise).

    The engine is "cranked" at about 1000 RPM. I cannot tell if it is running for real unless I look at scandata for the HV battery. It will show "discharge" amperage from the pack as it spins the engine over. If it never shows "charging" amperage, then the engine has not started and ran.

    Common faults are dirty (gooped) throttle body bore and MAF sensing elements. Less common are restricted or stuck shut fuel injectors.

    Posted via the PriusChat mobile app.
     
    #17 mr_guy_mann, Jan 6, 2025 at 5:28 PM
    Last edited: Jan 6, 2025 at 11:44 PM
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  18. Hayslayer

    Hayslayer Junior Member

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    Also, try to start it with the air filter lid removed. That will eliminate the possibility that air flow is being blocked by a rodent nest in the air intake area. You may also want to verify no one reverse jumped the car during the time it was sitting idle. that typically blows fuses in the underhood fuse box, along with popping the fusible link where the battery connects to the fuse box. Make sure the AM2 fuse is intact.

    Does any of the dash or MFD turn on when powering up the car?