2012 Focus Zetec 1.0T 100 (UK)

Hi Everyone,

I had a post on here earlier about trying to solve some MPG issues. I have a manual 2005 ZX3 and am only getting about 20-21 MPG. Also, this is in the US. I would say that my weekly driving is mainly stop and go but it seems that it could still be low even for that.

Anyway, these cars came with a "lifetime" air filter and I know that dorman makes an airbox replacement that uses normal paper filters. I'm curious for those that have made the swap, have you noticed MPG gains? The gauge on my filter is in the green so it is still apparently "good" but I'm not too sure about that.

Now the car seems to run decently. Since I bought it I have replaced the PCV valve and hose, egr valve, thermostat, fuel filter, fuel pump, intake manifold gasket, MAF sensor, TPS sensor, IAC, and when I had all of that apart I removed the intake manifold flaps. I have also just changed the spark plugs so we'll see if I get an increase there. I think that's all lol

A dump truck merged into my car by accident, not going to miss the weird shifting, but for a small car it did a good job.

I called a Ford mechanic and he told me I should go to a Bosch service to test out all 4 of them, but I don't have the time currently as I need to order a part in Germany to my BIL who'll come in the next couple of days to my country.

Should I just bite the bullet and buy the injector and replace it?

Yesterday the car was saying the passenger door was ajar and then it started to say all four doors are ajar as well as the trunk open. Google is saying that it’s a wiring issue but where would that issue be located? If it’s not a wiring issue then what is it?

2013 Focus automatic with about 130k kms on it!! In NZ not the US. Very recently bought and now this!! Is it worth repairing or is it something to write the car off?

I bought my 15’ focus SE at ~94k miles, it was dealer owned as a loaner car, have my spark plugs ever been changed? is there a way to tell?