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2015 Prius and Significant MPG Decrease

Discussion in 'Gen 3 Prius Fuel Economy' started by Tom Macke, Nov 30, 2022.

  1. Tom Macke

    Tom Macke New Member

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    Vehicle:
    2015 Prius
    Model:
    Four
    Hello All You Wonderful Prius Owners,

    Been a member for over a year, but been very busy and have not posted much at all. My issue is simple: My avg/blended mileage had decreased from ~52 mpg in 2017 (when I bought my used Prius) to the currently disappointing ~34 mpg I am averaging today. Is this due to a failing hybrid battery?

    Material facts:
    • regularly maintained on schedule
    • 150,000 miles
    • use LRR tires
    • conservative driving habits
    • So Cal climate
    • avg commute daily RT 25 miles (mostly freeway)
    Aside from that, the car runs like a champ with no issues. Runs smooth (for a Gen 3 lol), doesn't burn oil, never had any major repairs, etc.

    I suspect the hybrid battery is fading, not failed as I can still squeeze 1/2 a block of low speed EV only driving out of it, but it's my first Prius so looking for confirmation or other opinions and what to do.

    At 150,000 miles is it worth it to invest in a hybrid battery replacement? Or is the failing battery just the tip of the spear as a prelude to other mechanical issues waiting in the wings???

    Best Regards,

    Tom
     
  2. bisco

    bisco cookie crumbler

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    you can run a health test on the battery with the dr.prius app.

    it could be a dirty throttle body an maf, or something as simple as a dragging brake
     
  3. Grit

    Grit Senior Member

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    Bill norton would say withdraw $65,000 out of your checking account and buy a brand new Tesla. Azusa would tell you to buy a lithium battery and use his code to save a few bucks. Another user will provide 24/7 of free lithium tech support if you use his referral code instead.

    I say follow post #2 and return back with results but not buy the obd 2 module the rhymes with barista.
     
  4. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Vehicle:
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    And me: likely not relevant, but 150k? Cleaned EGR?
     
  5. nicoj36

    nicoj36 Active Member

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    Do this ECU reset, it will improve your mpg. Also get a bottle of lucas fuel treatment
     
  6. TheLastMojojomo

    TheLastMojojomo Active Member

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    Did anything happen proceeding the low mpg? Like maintenance or an accident of some kind?

    What speed is your freeway commute done at on average? Above or below 45 mph?
     
  7. AzusaPrius

    AzusaPrius Senior Member

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    Hah wow...I was going to comment in here to tell the OP to try disconnecting the 12v for 10 minutes.

    I never tell people to buy anything.

    I just talk about products I use and have on my prius and if possible try and work a deal with companies so that other prius owners can save some cash.

    I can give tech support and offer installation on the lithium battery.
     
    mikey_t likes this.
  8. Mr. F

    Mr. F Active Member

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    I've seen this video posted here as a solution to so many different issues that I simply had to check it out. Unfortunately, it is blatantly deceptive. There are two distinct scenes, with a cut at the 38-second mark.

    0:00-0:38
    The guys shows you the dashboard in READY mode with the slip indicator, both red and yellow brake system warning lights, and the ABS warning light illuminated steadily. The guy shows us the paperclip he'll use to "calibrate the steering angle sensor".

    0:38-3:04
    Cut to the paperclip having already been inserted into terminals 4 and 13 of the OBD2 port. The car is turned to IG-ON, the lights are blinking on the dash, he waits for 25 seconds, turns the car off, and removes the clip. When he turns the car back on into READY, all the warning lights are gone.

    The process described in the second scene is not some secret method for "calibrating the steering angle sensor"—it is the documented non-Techstream method for reading off DTCs related to the brake and airbag systems. The dashboard lights blink off two-digit codes which correspond to full DTCs, and these can be looked up in the repair manual.

    However, they also blink in a different pattern when there are no DTCs stored, and that is the pattern that we see in the video (tire pressure warning light blinking on and off every 0.25 seconds). The vehicle therefore did not find any current codes in Scene 2, which means whatever codes existed in Scene 1 must have been wiped before Scene 2 was filmed.
    upload_2022-12-1_20-1-3.png
     
  9. nicoj36

    nicoj36 Active Member

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    Yes well this method restored MPG on plenty of Prius drivers including myself. I have personally gained back 5mpg loss after doing this method. So did this guy Lost 10mpg After Replacing 12V Battery | PriusChat
     
  10. Bill Norton

    Bill Norton Senior Member

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    Never did so not......That guy's a spoiled rich kid d*k w/issues.
    But,,, if you eventually get tired of:
    dikin under the hood,
    and pumping that smelly stuff (and getting the smell on your hands) and sending your dollars out of the country,
    and changing the oil (at the interval of your choice)....

    There are affordable EV's out there,,, kind of....:whistle:

    It's the future, no matter what Mr. Toyoda says.:rolleyes:
     
    #10 Bill Norton, Dec 2, 2022
    Last edited: Dec 2, 2022
    nicoj36 likes this.
  11. Montgomery

    Montgomery Senior Member

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    Vehicle:
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    Model:
    Two
    I might try this. Ever since I purchased my yellow top battery at the 5 year mark, City driving mpg has dropped. This move seems to make sense. I have a few days off coming up and I will give this a try. Nothing to lose.
     
    nicoj36 likes this.
  12. ChapmanF

    ChapmanF Senior Member

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    I think you're being too harsh here. In scene 2, the rapid blink on the TPMS light tells you there weren't any TPMS codes. But we weren't really looking for TPMS codes. Other lights there are blinking some real codes. ABS is blinking 33 (C0210, right-hand rear speed sensor circuit), and ECB is blinking 36 (which just means "go look at your ABS code"). The VSC light is also blinking something real, but he moves the camera away before you can see what.

    All the same, there are still several things missing or wrong in the video:

    • Nothing that is shown in the video is a reset of anything. All that is shown is jumpering TC to CG, producing a display of trouble codes. There is a brake code reset you can do with the brake pedal while TC and CG are connected, but the video doesn't show him doing that. There are calibration procedures for the yaw rate and acceleration sensor and for the linear solenoid, but those involve jumpering TS (a different terminal), not TC, to CG.
    • He seems to think he's "calibrating the steering angle sensor", but that doesn't even have a calibration procedure for the skid ECU.* He's probably thinking of the yaw rate and acceleration sensor. That does have a procedure where you use the jumper wire and just turn the car on for a little bit ... much like what he's done here, only the jumper needs to be between TS and CG for that.
    • Even the procedure to calibrate the yaw rate and acceleration sensor only does anything if the ECU wants them calibrated. That would be a code 98 on the ABS light (which we can see, and isn't blinking that code), and/or a 36 on the VSC light (which the camera moves away from before we can see).
    • Calibrating the yaw rate and acceleration sensor wouldn't fix a right-hand rear speed sensor issue.

    So the video is kind of full of the things we try to help people not do: ignoring what your codes are telling you, applying random procedures without knowing what they do, jumping to bogus conclusions because of something you saw when you did. It could almost be used as a teaching example for all of those.

    From what I can see in the video, though, I'm not able to complete the story of why the C0210 right rear speed sensor code is gone at the end. No reset operation was ever shown. I'm not sure if those codes ever go away on their own after a certain number of power-ups without the problem detected. Some codes in some ECUs do. It would be extra funny if (a) he started out with a C0210 speed sensor code, (b) did stuff he thought was calibration of an unrelated sensor, only even that wasn't the sensor he was thinking of and also he did it wrong, (c) the C0210 just went away anyway, and (d) he thought "eureka! I have done it!".

    But I'm not completely hanging my hat on (c) yet.

    * There is a steering angle sensor calibration procedure for the parking assist ECU if your car has that feature. But the skid ECU relies on the yaw rate and acceleration sensor to do its own calibration for the steering angle sensor every time you drive. It just figures whatever the steering angle sensor says when you aren't skidding or yawing must be straight ahead.
     
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  13. Mr. F

    Mr. F Active Member

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    You're right, I did overlook the other codes. Looks like I've been rather uncharitable in characterizing the bloke as malicious when in fact he was just being clueless.
     
    #13 Mr. F, Dec 12, 2022
    Last edited: Dec 12, 2022