[xChristy]

So I've owned this 2007 European model Civic Type S (2.2 ctdi) for one month and I should clarify, i am a newbie when it comes to cars.

Background:
My fuel consumption was very high ever since i bought the car, and I though that might have been because I am not driving very economically and doing short city trips. I averaged 13l/100km.
It became very cold in my city lately , and the battery died on me once (though I was a reckless leaving ac and electronics on w/o engine running). I have managed to charge the battery back to an appropriate level and gave it a run to charge it back, no problems since then (except I kept having a Check Systems error for some time).
Now a couple days ago my battery almost died on me again (many errors coming on board, steering wheel moving hard) because i was forcing it again with a/c and electronics just after starting it while being cold. Now, i don't know if this is relevant to my issue, but i wanted to make sure you know this happened as it might be the cause of the following issue:

Issue:
My fuel consumption got way higher than before, right now staying at around 17l/100km.
I have stayed in my car for a couple hours some days ago, during which i have turned on the engine like once every 30 minutes to heat the cabin with some ac.
I don't think the engine was turned on for more than 1 hour in total, running on idle. That is when my average consumption went from 14~l/100km up to 17l/100km.
The average is not from a recent reset, i currently have 80km since last reset.
The fuel tank indeed lost way too much fuel, so it's not just the reading that's wrong.
Looking for possible causes, i found the possibility of having issues with my thermostat. That's when i realized that my temperature gauge is not even moving while i am using the car.

What do i need to buy /replace /do?
This consumption is killing me... And i am also afraid to use the car since i don't know if i can destroy other components using it in it's current condition.

Thank you everyone who will help in advance!

 

[EpistleNo.81]

Though it is not real likely, there could be a minor fuel leak. Just to eliminate the possibility, when the car is running, get on the ground and see if anything is dripping anywhere. OR if you can smell fuel. Look under the hood too.

Also, when the car is sitting there just idling for an hour, that wastes a good amount of fuel.

If the thermostat is stuck open, the engine cannot heat up properly and it will use more gas.

 

[xChristy]

Though it is not real likely, there could be a minor fuel leak. Just to eliminate the possibility, when the car is running, get on the ground and see if anything is dripping anywhere. OR if you can smell fuel. Look under the hood too.

Also, when the car is sitting there just idling for an hour, that wastes a good amount of fuel.

If the thermostat is stuck open, the engine cannot heat up properly and it will use more gas.

Thank you very much for the reply! I will check for any possible leak.
And yeah I thought it does waste some fuel, but didn't expect that much. It looked like my fuel tank dropped by something like 10-15%. That would be (I estimate) something in the range of 5-6 liters.
If that's normal, then no problem, good to know for the future. I just want to make sure it isn't running less efficient than it should.

 

[Asimo2007]

have you done a tune up? oxygen sensors original? vacuum leaks? you can spray starter fluid to the vacuum hoses in the engine bay while the car is running and if the rpms change, you have a leak there. i was getting low 20s mpg and it happened to be the evap box next to the gas tank, but i had check engine codes that accompanied the symptom. (07 EX Sedan)

 

[xChristy]

No tune up. Don't know about the sensors (as I said, new car for me, just 1 month) but dam thanks! Today my thermostat should arrive and i'll do what you told me in case it doesn't solve the issue.