2006 Corolla LE - MPG Decrease

[jackwetmore]

Hello,

I have a 2006 toyota corolla with almost 130k miles on it
over the last 6 months I have noticed a slow decrease in my mpg numbers and now I am getting between 25-26 mpg
prior to 6 months ago I have never gotten below 30mpg ever!
any suggestions on where to start looking for reasons that my mpg is plummeting?

 

[Savoir-Faire]

O2 sensors possibly.

 

[Scott O'Kashan]

How are you measuring the fuel economy? Most people don't measure it correctly.

Winter gas provides less miles per gallon than summer gas too.

 

[Savoir-Faire]

Run a scan, my Autozone does it for free.

 

[jackwetmore]

O2 sensor: wouldn't the check engine light come on? (I.e. It doesn't come on)

Fuel mileage measurement: I fill up my car every time at the pump and then reset my trip "A" until the next time I refill the tank

Autozone: I was unaware that they provided free scans, I'll try to stop by there today

 

[Savoir-Faire]

"O2 sensor: wouldn't the check engine light come on?", I'm not absolutely sure.
But with lower mpg and over 100K miles, Me? I would at least clean them. Also I would clean the throttle body/intake and put new plugs along with a synthetic oil and filter change.
I would run a scan though first to see if that comes up with anything related to a drop in mpg.
I shop around for Best Price on Good Guaranteed easily exchanged parts and do Most servicing myself. Example: if I replaced 02 sensors and that didn't remedy the problem my Autozone would take them back *if* I wanted to do so.
Good Luck!

 

[Scott O'Kashan]

O2 sensor: wouldn't the check engine light come on? (I.e. It doesn't come on)

Fuel mileage measurement: I fill up my car every time at the pump and then reset my trip "A" until the next time I refill the tank

Autozone: I was unaware that they provided free scans, I'll try to stop by there today

That's the way most people try to calculate fuel economy, but unfortunately it's not an accurate, as it allows all manner of uncontrolled variables to affect the miles per gallon calculations.

 

[IFMJohn]

if I replaced 02 sensors and that didn't remedy the problem my Autozone would take them back *if* I wanted to do so.
Good Luck!

What autozone do you go to??? No other parts store lets you do that. And I'm sure that autozone isnt supposed to either.

Why not just diagnose an issue rather than parts swap? You know that you can test your o2 sensors...

 

[jackwetmore]

That's the way most people try to calculate fuel economy, but unfortunately it's not an accurate, as it allows all manner of uncontrolled variables to affect the miles per gallon calculations.

How would you suggest calculating it?

I will run the diagnostic scan some time in the next week.

 

[salcuta88]

Did you check your tire pressure? Engine air filter? O2 sensor will highly decrease mpg.

 

[Donabed Kopoian]

I replace my upstream HO2S every 60k for optimum fuel economy. You might be due. I changed mine on my '08 Matrix and saw a 2-3 mpg increase (if yours is more worn, that number will be larger).

They won't throw a code until they are way out of parameter or completely fail. Best off getting it replaced.

Don't do the downstream, just the upstream. For the downstream, I only replace that one when I get a code for it.