P3191 and P0A0F/204

In Techstream, what is the significance of these highlighted items, trying to make sense of why the engine does not start and hoping someone can shed some light for me.
I've been troubleshooting a persistent issue with my grey Generation 2 Prius ever since I purchased it from a tow truck driver for $1,200 shortly after my accident in January 2023. The car had been sitting for nearly a year due to registration and operability issues, and I’ve been working on getting it back on the road for the last few months.

Recently, I've been dealing with error codes that have been particularly challenging to diagnose and resolve. The primary issue seems to be centered around the P0A0F/204 error code, which indicates an "Engine Failed to Start." Additionally, I received the P0125 error code, related to the Engine Coolant Temperature Sensor, and P3190, which indicates "Poor Engine Power."

The car shows symptoms where the RPMs gradually increase for about 10 seconds after starting, and then it shuts off, triggering a red triangle warning light. The engine doesn't seem to rev up properly when the gas pedal is pressed, which led me to believe that the throttle position sensor might be the culprit.

I've tested and replaced several components to pinpoint the issue:

1. Throttle Position Sensor: I initially replaced the throttle position sensor with one from a dismantler, but the issue persisted. The RPMs kept climbing without regulation, and the engine still failed to start properly. I recently cross-referenced Toyota part numbers and found a throttle position sensor at AutoZone that matched my research. However, even this new sensor didn’t align with the specifications outlined in the Toyota Tech documentation I have. The readings from this new sensor were also out of spec, leading me to question whether the issue lies elsewhere.
   
   
2. Engine Coolant Temperature Sensor: Since the P0125 code pointed to a problem with the engine coolant temperature sensor, I checked the resistance and manually bled the system again, hoping to resolve the issue. However, this didn’t make a significant difference in getting the car to run.
   
   
3. MAF Sensor: I also checked the MAF sensor by taking it off and testing it with some power to ensure it wasn’t the problem. The MAF sensor checked out fine, which left me more convinced that the throttle position sensor or something related to it was the root cause.
   

Despite all these efforts, the car still refuses to run properly. I'm beginning to suspect that there might be something more fundamentally wrong with the vehicle. The throttle body and sensors I replaced had markings from a dismantler, which could indicate that someone else had already tried to fix this issue before and failed. This makes me wonder if there’s a deeper problem with the car's electronics or some other component I haven’t yet considered.

The frustration lies in the fact that no specific error code is being thrown to indicate precisely


any guidance is appreciated.

 

does this help any?

 

here are the others I grabbed with the first image I posted

 

Understood... I'm realizing now that I have to save the data after starting the recording in techstream before I proceed to put the car in Ready mode to record everything to nail this down. I tried replacing the ECM thinking it was bad and tested the resistance to all of the sensors since P0A0F/204 diagnostics says to clear relevant dtcs first.



i need to go back and check the dates of each of the data points ive saved, the realization that under DATA LIST the DATA 3 has the data from the one recording of the car that I did. The others in OPERATION doesnt have that detailed data. You see, im realizing
P3191 or P3190 were the codes returned plus the linear offset one I wasnt worried about yet. the only sensor whose resistance didnt match the standard was the throttle position sensor. the brand new sensor at autozone read just like the replacement from the dismantlers where only 2-4 and 3-4 was not 1.8 and higher. I plan to go through and check all sensors once more... its just... trying to track this down has taken wayyyy longer than it shouldve and hoping by recording something could help pin point this. hence my ask of what is the significance of the highlighted mustard color values in the techstream app?

I went to look at the file I did record, and did a screen capture... does this help you identify where this problem could reside and if not, where in Techstream would you recommend I start from other than the codes? Id like to like there is a blazing indicator somewhere in this app to monitor what is triggering this DTC... right?

 

Roger that ghostrider! I need to get back to the car so I can record PIDs from Engine and ECT.

Why on earth the car just doesn't throw a DTC for the problem is beyond me!

 

If AI is involved, it might as well fix the problem after it diagnoses the issue!

 

hmmmmm... roger that ghostrider!

I uploaded the TSE file to my webserver... this might be a better way versus me making screenrecordings right?

https://black.jmyntrn.com/2009_Prius_1NZ-FXE_8-13-2024%2023036%20AM.TSE

unfortunately... i didn't bring my HV charger this morning... HV battery died but it dit get one crank session going!

 

did that file work for youi?

 

Well... i finally built a grid charger... got the SOC up above 50% and at first P3191 then a reset and restart for P3190 to be thrown instead.

Interesting enough..

• Throttle Position Sensor (measured between pins):
  • 1 and 4: 1.694 kΩ
  • 1 and 3: 1.616 kΩ
  • 1 and 2: 1.28 kΩ

These values should typically be within the range of 1.2 to 3.2 kΩ for the VC (1) to E2 (4) pin, and 1.8 to 10.5 kΩ for the VTA1 (2) to E2 (4) and VTA2 (3) to E2 (4) pins at 68°F.

The value between pins 1 and 4 (1.694 kΩ) is slightly below the expected range, which might indicate a potential issue. The other readings also seem lower than expected for the VTA1 and VTA2 pins. But when I tested a new sensor, the values were roughly the same.

AI tells me...


Based on the specific data you've provided in the images, the most significant potential issue appears to be related to the throttle system. Here’s why:

1. Throttle Position and Throttle Motor Duty Cycle:
   
   • The throttle motor is showing a current draw (around 17.2%) and the throttle position sensors show minor variations, but they are not opening fully as expected. This suggests that the throttle body might be partially stuck or the throttle motor isn't responding correctly, leading to insufficient air intake.
2. Throttle Motor Current:
   
   • The fact that the throttle motor is drawing current but the throttle position isn’t changing significantly suggests the motor is working harder than it should, potentially indicating a mechanical binding or electrical issue within the throttle body assembly.
3. Throttle Fully Close Learn:
   
   • The throttle fully close learn function doesn't appear to be completing successfully, which could indicate that the throttle body isn't able to close properly. This could cause the throttle to be stuck in a partially open position, which would prevent the engine from starting or running correctly.

Specific Problem Suspected:

• Throttle Body Issue: The primary suspect here is a throttle body problem. It could be mechanical, such as carbon buildup causing the throttle plate to stick, or electrical, like a failing throttle motor or sensor.
  
  
• Throttle Motor or Wiring Issue: There may be an issue with the wiring to the throttle motor or the motor itself. If the motor isn't functioning correctly, it won't be able to move the throttle plate as needed.
  

Immediate Action:

• I recommend inspecting and cleaning the throttle body thoroughly if you haven't already. Check for any carbon deposits or physical obstructions that might prevent the throttle plate from moving freely.
• If cleaning doesn’t resolve the issue, consider replacing the throttle body or testing the throttle motor and position sensors to ensure they are functioning correctly.

I cleaned the TB out.. and put another on that had the sensor and motor resistance not abnormally out of line.

makes no sense why the car wont throw a specific code with the issue... almost at my wits end with this car.

 

please see the below.

 

OKAY! Thank you!

That's the part that I wasn't getting. This is a car I bought under the assumption bad HV battery, installed the latest and greatest lithium cells... then realized the gas pump was bad then swapped the tank... shortly after and when I should've started building the grid charger, I realized the motor was seized. I was gifted a JDM motor and after swapping over all from old seized sensors and components thinking I just wanted to get it started and I would then proceed to do the plugs and all else not "pressed" to get it done. I hope I find the smoking gun and it's running before Ive end up just going down the route of every sensor/plug/injector out and replaced with brand new. pulling part numbers now and gonna phone a friend in the morning on these parts. I grabbed an electronics cleaner that i might use and pull things apart once more before the next step would be replacing everything with a connector on this motor!

side note, being able to charge with the easy grid charger... versus... having to take that ____________ mother of a ____________ battery harness on and off while diagnosing through all this... is such a large weight lifted compared to the smart rc charger and putting them all in parallel.