Why am I getting horrible gas mileage?

Hi, I have a 04 Tacoma 2.7l I just recently purchased, it’s getting around 12mpg. It is reading some codes such as P0446,P0441,P0442, and P0401. Basically a EVAP leak and a EGR problem. I was just wondering if these could make the gas mileage that bad? I already changed the spark plugs, air filter, cleaned MAF sensor, and Cleaned the throttle body. It does have a faint smell of gas after driving if anyone could point me in the right direction as where to start I’d appreciate it.

 

Well one of the symptoms of a bad egr is poor gas mileage. Replace the sensor and see where that takes you

 

The EGR sensor is just a temperature probe and rarely if ever goes bad. It is likely that your EGR is either stuck open or closed and you may want to start by trying to fix that. But your gas smell and EVAP leak can equate to either bad vacuum lines or possibly rusted out breather tubes. Might want to start by giving all of your vacuum lines a once over.

 

Could also be a small fuel leak?

 

I checked all the lines they’re all good no cracks or anything like that. I took off the egr valve today to see if I could clean it then read it could just ruin the hole thing. How could I tell if it’s stuck open or not? Thanks

 

Could be. I got under it and checked but didn’t see nothing I do have a after market gas cap and it does smell around there but I didn’t think it could cause a huge drop in gas mileage?

 

Well you have an 04 so there are vacuum lines back there for the charcoal canister (the thing that is supposed to catch the fumes) so I'd check around it as well

 

Yeah I’ll have to check that out too. Thanks for the help!

 

I doubt the gas cap would cause that. It may be causing issues with your P0442 code though. My truck also has an aftermarket gas cap and occasionally throws that code if I don't have it on there exactly like it wants. It may be worth grabbing one that is OEM to test and see what happens.

 

Yeah I probably will just to see what happens and cut that out of the equation.

 

What sensor?The temperature sensor?