Attention Prius Owners, I believe I have discovered a previously unknown Mechanism of Low MPG.

Have u tried sweeping or reprogramming the throttle body Just an idea. I know on some cars this can fix a lot of the glitches


iPhone ?

 

Just curious...has anyone tested out if the issue persists after swapping out the traction battery? I'm wondering if the ECU is triggering a different usage profile based on what it determines the health of the battery pack is?

 

I had a friend with a Prius report the low 40s mph and then got the traction battery replaced and said she's back in the 50s now.

Like others have said, I noticed mine dropping immediately when I replaced the 12v battery back in 2017. I'm lucky to get 42mpg on mine and I never use the AC. I've got 274k on original traction battery 2009

 

Not a Toyota tech, but you’re correct that many “test conditions” in modern cars require more than just starting the car and driving. Time spent at or above a specific speed, ambient air temperature, cold soak (where the car gets up to temp and then back to ambient before restarting), some or all MIL being off and having passed their own checks, and more, can be requirements for cars to pass their own self-tests. Besides this, some systems are gating items for other systems. That is to say: until system X has passed its tests, system Y will not attempt to run its tests. Factory technician training documentation should have retirements to fulfill these tests so they can meet them using your car after certain repairs, but I worked at an independent garage and know only vagaries, not specifics.

 

In addition to what was said in the last post, I'm pretty sure the start-stop style of driving of a postal worker is never going to get the Prius configured for max MPG.

 

This stuff is too thick for me, or I'm too thick for it.
Either way, I'll give it a pass. I prefer the old fashioned way; I record my mileage and fuel quantity at fill-up each time, and do the math.

 

You can easily fix this issue by replacing your 12 volt battery with a brand new high quality.
Everyone who does this and makes a video about it will recieve $2500.

I gave Mr mojo the solution to this problem years ago and he refused to try it, he tried everything but the correct solution,
Don't repeat his mistake.

 

Is there a new billionaire or 12V battery store owner on the forum?