Gen 3 - J0V Recall - Bad MPG - ECU Swap

Hey Prius Friends. I have a little story to share.

July 2019 I took my 2013 Toyota Prius in for the Inverter Software Update Recall J0V. The car at the time had 209,000 miles on it and averaged 43 miles per gallon. The recall was performed by Hollywood Toyota and picked up a few hours later.

After getting the car back I realized my fuel economy was not the same. I thought, the car needs to adapt due to the ECU being updated and will relearn my driving. A week or so later I realize nothing has changed. I’m getting 32/33 average and can not seem to get it back in the 40’s.

I started doing some research and found I was not the only one with this issue. Thinking there is little chance it could be the recall update, I decided to look further into some maintenance that I should perform that has not yet been done. I removed and cleaned the: Intake manifold, EGR system, Throttle body, Mass Airflow Sensor, Injectors. I removed and replaced the PCV Valve, Spark Plugs, Air filters. I may be missing a thing or two. Because I had heard of a stuck caliper pin causing a mileage reduction, I decided to remove and replace the front brakes, rotors, and lube the pins. Removed the read tire, lubed the rear caliper pins.

Throughout these different things performed on the car from January 2020 til a month or so ago (August) still no change. 32mpg is the somewhat new average. Over a year of 32mpg average.

Late August I took the car back to Hollywood Toyota and had a health check performed. A couple hours later the service manager and tech shared with me that the car checked out fine and they found nothing wrong. So on September 8th I took the car to Claremont Toyota and had a health check performed. A couple hours later, I received the same info. Nothing found, can’t seem to find a reason as to why it would not be performing at the previous average which it had for two years of me owning it prior to the recall.

Yesterday, after a decent amount of research I decided to move to pretty much the only next step I can think of. While Toyota can not revert or remove the update, taking it back to the previous state of software, I can remove the software from my car by removing the ECU all together and swapping it with one I know has not received the recall update. I found one online and ordered it after speaking with the company, running the VIN to confirm the recall was still open and not performed. This is where I currently am in the story. It arrives in a few days, I will swap it out, and update this thread on what the results are after putting some miles on it. Feel free to chime in, share your experience if similar, or any constructive advice you might have.

Part Number for ECU: 89660-47514

 

Hey there. Great questions. My response will be brief as I have to head out for a bit. ECU does not have to be matched. You can do a swap, then reset the immobilizer by jumping the 4 and 13 pin for 30 minutes in ACC-on mode. This will pair the ecu to car. The VIN will still be the previous VIN and may be updated in the future if desired. As for resale, or registration I’m not concerned there as my first (2005) and third (2013) Prius were totaled, one with 291,000 miles and the other with 152,000 miles. My second (2008) I gave to my parents with 164,000 miles still going strong.

If I wanted to have the recall performed on the ecu I am installing it would be no problem having it performed. As for the recall in general, I have driven my first 2013 162,000 miles with no issues, and this one 209,000 until the recall was performed. I’ll take my very slim chance of it stalling (while I am curious how many this has actually happened to) than getting 10 miles less per gallon.

Thank you for your concern, but I do plan to move forward with trying to locate this issue. Toyota dealerships can not locate the issue and Toyota Corporate has taken all my notes and informed me that they do not have anything in place to address this concern and are no help to me at this time. They recommend to continue to deal with dealers, which I have found to be useless over my 12 years of owning Prius’ as it is.

(Previously I was a Sales Manager of a Toyota dealership and would say the same thing then too.).

 

Hi. Which is why I decided to do the crap ton of maintenance I did to see if it was caused by something other than the recall. While I’m not the only one with the issue right after the recall I’d believe it is the recall. No luck with everything performed.

I did run a Dr. Prius battery check maybe 6 months ago (approx 6-7 months after recall was performed) and hybrid battery checked out fine. Considered that as a possibility however seems with dealer check and Dr. Prius it is fine. Before I touch the hybrid battery or 12V I plan to change ecu. If my mileage comes back after the swap, we know it is not anything battery related. If it does not, then it could potentially be 12V or HV battery related.

 

Thanks for doing some math for me.

The ecu cost me $150. If it fixes the issue, it’s well worth the headache on my end. All the other things I did as I have done all the maintenance was simply things that needed to be performed anyway.

Obviously if I had paid a shop to do all of this it may not have been worth the cost. As for the two dealerships, there was no cost involved.

I appreciate and respect your response. I have thought it out, nearly all the variables, and find it to be worth it at this time. I will update you as to whether this is the fix. If so, I’d imagine many others would have interest in doing the same.

For the safety concern... back to my earlier post... just how many have experienced said safety concern for it to truly be a safety concern. VW had some major issues lately and unfortunately that changed everything when it comes to recall and safety type issues.

 

By the way, I should mention. I have followed you for years on here (even though I just created an account) and have appreciated your responses over the years on people’s post.
Thank you for taking the time.

 

That is correct. 4 and 13 in the orb plug.

Put in a jumper.
Turn car to ACC-on (by pressing button twice)
Leave for 30 minutes.
Turn car off
Remove jumper
Start car normally.

 

Yeah. Toyota checked the system, as well as my own test ran through Dr. Prius. Agreed. The engine is running more and longer, hence the issue. This is also unfortunately what the recall does as well. Limits the inverter output which causes more strain and use on the gas engine. (Per the Toyota tech and reading into it) .

 

Thanks for the little compliment. I will say, 12 years of owning these cars and doing my own maintenance for the most part, you could ask a question about these cars and I could most likely answer it. All the way down to what size bolt is where. ‍

What I have not had to venture much into is the electrical management system.

I agree with you. There are far more with this issue just not speaking out about it or knowing where to do so. I posted this in the Toyota Prius Owners Group in FB for those who may be having the issue to keep them informed and found there is another who spoke up with a loss of MPG after the recall.

A commenter just above mentioned that others found their mileage came back shortly after the recall was done and why I waited so long (basically a year) to take it back to have tested. Little did I know it could be the recall, even after knowing the mileage plummeted after receiving the car back from the dealer. So I did as mentioned above and started doing other maintenance which the car would need anyway to get it back. Wednesday or so can not get here soon enough.

I’ve done basically everything except:
Replace either battery, Replace Mass Air Flow Sensor (has been cleaned), Flush transmission fluid, flush radiator fluid, replace inverter/motor/or anything involved with these electronically. I think that’s about it. I’ve literally removed nearly everything and cleaned and put it back on in an attempt. That damn EGR. Still thinking back to how clogged they get. For those who have not pulled and cleaned yours... if you are anywhere close to or over 100k on yours, it’s beyond needed. Do it! And be patient, and change your spark plugs while you’re at it since you have to remove the windshield wiper assembly to get to either of these and perform the maintenance.

That’s all for now.

 

Per Toyota, this ECU is described as...

“Computer, Engine Control. Engine Control Unit. Powertrain Control Module.
A module in a vehicle used to monitor and control many components of the vehicle's engine management system”

I have the Toyota maintenance printout for the recall that the tech would receive. Looking through it again now.

 

Based on your experience following this issue for a couple years on here. If it is correct that this is not the correct part and does not fix the issue, what parts should be replaced if the idea is to remove the software update from the car by removing the part.

What is your advice knowing what you have read in the past, and in my post?