My 2007 toyota had a battery and serpentine belt replacement now low gas mileage on 2007 Toyota Corolla

Since repacing both gas mileage from 33 mpg to 27. Brought it back to repair shop tjey said the could not find anything wrong

Asked by for the 2007 Toyota Corolla
This is just a coincidence, your mpg would not have been affected by those parts being replaced! If they had knocked something loose, the check engine light would be on! Look elsewhere for a the loss of mpg, recheck it to start with while driving your routine daily travlels.
This has been going on for 3 weeks now starting with the first gas fill after the r\preventative repairs. Nothing else has changed. I have been reading about the ECU needing to be reset after replacing battery
No that's not true! The computer/ecu would have relearned those strategies before you got home!!!★ Also most professionals or repair shops use a power saver when battery is disconnected so that will not happen!! Recheck your mpg just to be sure.
thanks for your help but just filled up again yesterday...27 mpg...before battery replacement average good answer yet:)
Hope you get one! However there may not be one!!
1 more answer , 1 more comment
poss they reset computer when repl battery,fuel trim will take over and may repair itself
I hope so tho this has been going on for 3 weeks now since battery and serpentine belt replaced. thx
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