code P3191

DTC P3191 means engine no-start. This is a well-known issue with Classic.

There are a few things that you can do to take care of this problem:

1. Clean the throttle body interior and throttle plate to remove the black gunk that you'll find within. Make sure the throttle plate rotates freely when the car is IG-OFF and you turn the spring-loaded shaft.

2. Make sure that the iridium spark plugs are in good condition; note the service interval is 60K miles. While you are at it make sure the engine air filter is not dirty.

3. Make sure the engine oil viscosity is 5W-30 and the oil level is not above the top dimple on the dipstick.

4. After taking care of the above, if you still have trouble, then check your engine ECU part number. The latest version has part number 89661-47054. This allows more time for the engine to start before logging the DTC and turning on warning lights. If your ECU is downlevel then you can buy a salvage ECU for ~$300 and that should take care of the problem. Also do a search for TSB EG011-03, for more details.

Good luck.

 

Upgrading the ECU to 89661-47054 did not fix it for me. Neither did replacing the MAF sensor.

P3191 happens for me on start in cold weather or after it has rained. I can reliably work around it by shifting from Park into Neutral while MG1 is still trying to start the engine. This does something to get the engine started properly.

T-SB-0180-09 is the latest TSB on this issue and does not mention ECU replacement as a solution.

 

Shifting to neutral removes all load on the engine. It could be that it is just barely starting, i.e., producing enough power to spin itself around, but is tending to stall under even the minimal electrical load being put on it when the car's not in neutral.

The reasons for a gasoline engine being balky to start are pretty much the same old suspects, even if there's a lot of fancy tech around it.

 

Fuel - Spark - Air
The Three Amigos!

 

And compression, the annoying guy who's always following them around.

 

... for anyone else who runs into this problem in the future, part 89661-47054 did in fact fix the problem after all. The very first startup after installing that part threw a P3191, and then I posted my complaint, but it hasn't happened since at all this winter...

 

Hello I also have the problem of starting the engine
I live in Italy and mine is a Prius built in 12/2009 with 155,000 miles
The error codes are P0351-P0352-P0353-P0354-P3190-P3191
I took the car to Toyota and they diagnosed the engine ECU malfunction
I know they emptied the tank and found dirty gasoline now replaced with clean gasoline, they replaced spark plugs but the car did not start
They say it is definitely the engine control unit
Now being very expensive, I parked the car outside the dealership and I am removing the ECU to buy a used one and copy the files
The number is 89661-47280

In your opinion is this the correct diagnosis?

 

Those codes refer to the ignition coils. Having all four of them does suggest maybe something that is common to all four ignition coils. The ECU would be one such possibility.

I think I would begin by looking in the repair manual to learn what is the exact detection condition for those coil codes. Then I would probably do some poking around with a multimeter to see if I could find why the detection condition exists.

 

At the dealership they removed the spark plugs with new ones and the car did not start because they say that an incorrect voltage arrives at the spark plugs due to a malfunction of the engine control unit
Tonight I dismantled the engine control unit and tomorrow I will take it to a repair center to see if they will be able to extract the data and possibly buy a used control unit and enter the data

 

You may get more help by posting your issue in the forum dedicated to your year of Prius. This is the forum for the 1st generation. Good luck!

 

Ho appena aperto il post nella sezione corretta
grazie e buon proseguimento