Yes, if your MAF is dirty that may affect how much fuel the car injects, and thus your fuel economy. Check the MAF circuit and test the MAF sensor to make sure it is operating properly. You should be able to find the procedure in your vehicle’s factory service manual. If you decide to try cleaning the MAF, use MAF sensor cleaner and nothing else.

While you’re in there, I’d also check the basics – when was the last time your engine air filter and fuel filter have been replaced (assuming the fuel filter is serviceable)?

Hi Sean. Could MAF sensor effect fuel consumption and MPG? On average I should be getting around 40mpg on Mondeo mk4 2.0 diesel but seem to be stuck on 33.7mpg even on long smooth drives. Also the fuel guage flactuates. DTC says P00BD but no ELM.

Agreed 100% about keeping speeds down on public roads. Since the WRX is a sporty car, perhaps Rhodora wishes to track the vehicle. If so, speeds in excess of 140 km/h happen every single lap.

Don’t drive 140 km/h and see if the problem persists. If it only happens when reaching or driving 140 km/h its a small sacrifice and will probably save your life to slow down. They dont just put in “lot’s of warning indicators” to see how colorful they can make instrument cluster, they are there for a reason. I doubt its the fuel pump, if its not covered under warranty stay the hell away from the dealers. Find a good reputable local mechanic instead to diagnose problem but before that I would start by slowing down.

Off forum topic but worth a mention, Im not sure people realize how little time is saved by driving somewhere fast. This was put into perspective for me when a three hour trip was driven by both myself in one vehicle and my wife in a separate vehicle. We left at same time, I drove like a maniac much of the time reaching speeds of 150-160km/h I got home, heart pounding, hands sweaty, knuckles still white, she pulls into the driveway 8 minutes later. I said wow, you musta been flyin too, she say no, 110 whole way. 8 minutes I saved, the time it takes to get a coffee. 300+km trip, thats a lot of km’s and a lot of people to be endangering lives. I dont speed anymore, risk vs reward is not worth it.

I dont have a direct suggestion to the actual question but will suggest to you this to save you money on a weekly basis, quit putting mid grade fuel into vehicle. Regular 87 octane fuel is all that is required by 99% of vehicles that are daily drivers and using mid or high octane fuel absolutely will NOT give you better mileage, simply better performance (for which mileage is not an indicator of).

Could be electrical, check relay and you’ve determined fuel not reaching injectors so dont waste time looking at them, youve done a more then adequate pump test so you know pump is working, only leaves lines. Go back and inspect again between injectors and tank. Check at connections and fittings and that no part of line is kinked or pinched.

To trace for sure, starting right at tank, unhook fuel line from fitting on tank that is directly connected to pump and connect a rubber hose to fitting running to bucket. Have someone else start vehicle and watch the pressure as it sprays into bucket, if its good, hook line up to tank and move down the line to next junction, fitting or connection of any type. Disconnect there and do same thing with rubber hose into bucket. When you see an obvious pressure change or lack of pressure youve found your clogged part of line and/or clogged fitting. This is time consuming and can be labour intensive if doing without a lift but it is 100% definitive.

Parking on a hill
bad sending unit
bad fuel gauge or cluster
float stuck

If no performance issues with vehicle, and dont want to pay just to find out, do some math and keep track of fuel level in your head or on note pad. You will need the actual L/100km or mpg the vehicle gets. Can be found usually within the vehicles information on instrument cluster. If not, its more math first.

Sounds like they shot the parts cannon at your car, which gets pretty expensive. Try to find a mechanic in your area who does really good diagnostics work. It’s worth paying a small amount for a proper diagnostic, then you can go from there once you know what’s causing the problem.

Well, this is the very reason new cars come with warranties. Sometimes parts are defective and these problems usually surface pretty quickly in your ownership experience. I would get the fuel pump replaced under warranty and see how it drives. It should cost you nothing but the time it takes to drive the car to and from the dealership. The car should be perfectly fine after that.