# 2012 Toyota Camry Hybrid - Mileage Deterioration After Tranny/Spark Plug Change **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** toyota, camry\ **Created:** [August 9, 2019, 1:22am UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320 "2019-08-09T01:22:58Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Pelitera](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pelitera](https://community.cartalk.com/u/Pelitera)\ **Post date:** [August 9, 2019, 1:23am UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/1 "2019-08-09T01:23:00Z")
losing mpg, since transmission and spark plug change ---
**Author:** ![shanonia](https://avatars.discourse-cdn.com/v4/letter/s/9de053/32.png) [@shanonia](https://community.cartalk.com/u/shanonia)\ **Post date:** [August 9, 2019, 4:15am UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/2 "2019-08-09T04:15:39Z")
If you have a question, please ask. Describe what was done, and why, and the before and after performance. ---
**Author:** ![PvtPublic](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/pvtpublic/32/13089_2.png) [@PvtPublic](https://community.cartalk.com/u/PvtPublic)\ **Post date:** [August 9, 2019, 9:51am UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/3 "2019-08-09T09:51:57Z")
> [@Pelitera](#): > > losing mpg, since transmission and spark plug change Congratulations, thanks for sharing. ---
**Author:** ![PhantomPatriot](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/phantompatriot/32/20713_2.png) [@PhantomPatriot](https://community.cartalk.com/u/PhantomPatriot)\ **Post date:** [August 9, 2019, 12:01pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/4 "2019-08-09T12:01:39Z")
Cmon guys, his question is obviously “why is this happening, and how can I fix it?” Was the transmission completely replaced? We’re all spark plugs changed? Try to provide some more details about the issue (like why you had the work done in the first place). ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [August 9, 2019, 12:10pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/5 "2019-08-09T12:10:54Z")
i bet he had the trans serviced. or maybe not ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [August 9, 2019, 1:38pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/6 "2019-08-09T13:38:28Z")
> [@bpinard\_154481](#): > > Cmon guys, his question is obviously “why is this happening, and how can I fix it?” You are new here. I suspect, over time, you, like we, will get really, really, tired of folks that can’t ask an actual question nor give any useful information at all. Playing _20 Questions_ gets old after a while. ---
**Author:** ![PhantomPatriot](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/phantompatriot/32/20713_2.png) [@PhantomPatriot](https://community.cartalk.com/u/PhantomPatriot)\ **Post date:** [August 9, 2019, 1:40pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/7 "2019-08-09T13:40:52Z")
I may be new here, but I’m not new to forums. I’ve seen many communities rise and fall over the years. A helpful attitude benefits everyone. If you don’t want to help or just want to post snarky remarks, then don’t post. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [August 9, 2019, 1:43pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/8 "2019-08-09T13:43:17Z")
> [@bpinard\_154481](#): > > Cmon guys, his question is obviously “why is this happening, and how can I fix it?” Sorry, but if someone wants an answer to a question then they should at least make an effort to clearly state the question. ---
**Author:** ![Pelitera](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pelitera](https://community.cartalk.com/u/Pelitera)\ **Post date:** [August 9, 2019, 3:26pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/9 "2019-08-09T15:26:40Z")
Ok, Let me be clear. 2012 camry hybrid. I just changed the fluids in the transmission and the coolants . The spark plugs, all of them. My mpg has dropped. DO YOU KNOW WHATS UP? HAD NO PROBLEMS PREVIOUSLY. ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [August 9, 2019, 3:55pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/10 "2019-08-09T15:55:30Z")
Who performed the service? If it was somebody other than the dealership, it is entirely possible that they didn’t use the correct specification/brand of spark plugs. Your Owner’s Manual should state the specification and brand of spark plugs (typically NGK and/or Denso). Are you sure that the correct ones were installed? ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [August 9, 2019, 4:10pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/11 "2019-08-09T16:10:48Z")
And was the correct fluid used for the transmission? It’s not a normal transmission, it’s a set of planetary gears, and I bet it uses a special fluid. I would only get it from the dealer, just to be sure. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [August 9, 2019, 4:13pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/12 "2019-08-09T16:13:48Z")
> [@Pelitera](#): > > My mpg has dropped By how much and how are you checking it. Only the pen and paper method will be accurate . Have you given it more than one tank ? ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [August 10, 2019, 1:23pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/13 "2019-08-10T13:23:36Z")
our 2012 prius, now gone, had a big display for the mileage. hard to miss. drove to work. 31.2 miles, avg mpg is 53.2 mpg. everday the same thing. i suppose if it said the mileage for trip was 52.8 i might even notice. or maybe not. prius was ALL about mileage. look what you are getting. woohoo. maybe the camry is more subtle and you have to ask it? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [August 10, 2019, 1:31pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/14 "2019-08-10T13:31:33Z")
> [@Pelitera](#): > > My mpg has dropped. By how much? Has it gotten better over time? How much time did you give it before you posted? How many miles are on this car? How are you checking the mileage? Have you recently changed the tires? There is 6 of the 20 questions. > [@Pelitera](#): > > DO YOU KNOW WHATS UP? Please stop yelling, all caps won’t help, answering questions might. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [August 10, 2019, 4:32pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/15 "2019-08-10T16:32:52Z")
I think people here are plenty willing to help but to bring up the old saw; the devil is in the details. Without the minutae it will be near impossible to even guess at what is going on. This is not meant to be snarky at all so please don’t take it that way but right now your complaint is equivalent to a “Doc, what’s wrong? I don’t feel good” statement with no ensuing details. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [August 11, 2019, 12:11am UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/16 "2019-08-11T00:11:00Z")
The most common reason for an mpg decrease is the engine coolant isn’t reaching the correct operating temperature. Since part of the work you did was replacing the coolant, suggest to focus on the cooling system as the cause. Is the dashboard coolant temperature gauge acting like it used to? ---
**Author:** ![Pelitera](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pelitera](https://community.cartalk.com/u/Pelitera)\ **Post date:** [August 17, 2019, 3:52pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/17 "2019-08-17T15:52:45Z")
Yes , the coolants were replaced. The dealership did it. ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [August 17, 2019, 3:54pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/18 "2019-08-17T15:54:34Z")
> [@Pelitera](#): > > the coolants were replaced. Yes, but that has nothing to do with the temperature that the coolant reaches. It is entirely possible that the cooling system thermostat is stuck in the open position, and it needs to be replaced. That being said, I don’t think that my earlier question regarding the spark plugs was answered. 🤔 ---
**Author:** ![Pelitera](https://avatars.discourse-cdn.com/v4/letter/p/59ef9b/32.png) [@Pelitera](https://community.cartalk.com/u/Pelitera)\ **Post date:** [August 17, 2019, 3:55pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/19 "2019-08-17T15:55:18Z")
All fluids were changed at the dealership. The spark plugs, I did. ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [August 17, 2019, 3:56pm UTC](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320/20 "2019-08-17T15:56:49Z")
> [@Pelitera](#): > > The spark plugs, I did. Are they the same brand/specification that is listed in the Owner’s Manual? [Next page](https://community.cartalk.com/t/2012-toyota-camry-hybrid-mileage-deterioration-after-tranny-spark-plug-change/146320.md?page=2)