1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Gas Mileage dropped to 28-29 MPG's after new Catalytic Converter and Shield installed. WHY?

Discussion in 'Prius c Fuel Economy' started by Owner of "Little Green", Aug 16, 2022.

Tags:
  1. Owner of "Little Green"

    Owner of "Little Green" Junior Member

    Joined:
    Jan 13, 2018
    10
    2
    0
    Location:
    Boulder, CO 80304, USA
    Vehicle:
    2006 Prius
    Model:
    N/A
    I had my Catalytic Converter stolen in June and paid to have a shield put over the new CAT. Immediately after that my MPG's dropped to 28 to 29 MPG's. What happened?
     
    #1 Owner of "Little Green", Aug 16, 2022
    Last edited: Aug 16, 2022
  2. rjdriver

    rjdriver Active Member

    Joined:
    Apr 7, 2012
    407
    168
    0
    Location:
    Rhode Island
    Vehicle:
    2012 Prius c
    Model:
    Three
    Did you have the Cat replaced at a Toyota dealer?
     
    #2 rjdriver, Aug 18, 2022
  3. priusCpilot

    priusCpilot Active Member

    Joined:
    Mar 6, 2012
    651
    210
    0
    Location:
    LA
    Vehicle:
    2012 Prius c
    Model:
    Four
    Do you have a Prius C or a Prius 2006 Gen 2?
     
    #3 priusCpilot, Aug 18, 2022
  4. audiodave

    audiodave Active Member

    Joined:
    Feb 3, 2017
    788
    269
    0
    Location:
    US
    Vehicle:
    2004 Prius
    Model:
    Five
    Is that a calculated tank?
    Posted via the PriusChat mobile app.
     
    #4 audiodave, Aug 18, 2022
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,129
    50,045
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    is it a catshield?
     
    #5 bisco, Aug 18, 2022
  6. Redline96

    Redline96 New Member

    Joined:
    Sep 13, 2022
    6
    0
    0
    Location:
    OKC metro
    Vehicle:
    2014 Prius c
    Model:
    Two
    There's a few variables I can think of. If the exhaust header and the catalytic converter are separate then that could do it; Toyota (/OE) design has the converter and the exhaust manifold combined. Either one, or both, of the oxygen sensors could've been damaged with the removal. It's possible that the new installer did damaged O2 sensors, but highly improbable. An exhaust leak could cause it (any new smells)? Do you have a check engine light on or a heat coming into the cabin from the floor? If an aftermarket converter was put in, it might be too restrictive for the Prius C's design parameters. Did you get a used converter? Used ones could be clogged and cause the engine to work harder.
     
    #6 Redline96, Sep 21, 2022
(You must log in or sign up to post here.)