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62 Plate Cmax Drop In Mpg


Timitfc
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Hi All,

Over the last 2 weeks i have noticed a sudden drop in MPG in my 2012 Cmax 1.6 TDCI Titanium. I used to receive on average between 44-48 MPG around town / driving to and from work (10 miles trip).

However I have recently noticed that on the same journey, and same usage getting around 40-41 mpg - engine sounds fine and doesn't appear any loss in power.

Does anyone have any suggestions on what to check as something isnt quite right!

Thanks

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Diesel engines take longer to reach optimum operating temperature in colder weather & are as a result less economical.

How are you measuring the vehicle's average m.p.g. ?

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I use the trip computer for ease, however I know this isnt true MPG and i actually get 2-3 mpg less than this.

I have noticed the fuel guage go down further based on miles done so I assume its not a sensor issue? Would it be worth getting a diagnostic done? Would it bring up anything that the car wouldnt tell me?

Thanks for your help!

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When was the fuel filter last changed ?

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It had a service about 4k miles ago so I would assume then.. however I will need to check to what exactly was done - could a blocked / clogged fuel filter provide a sudden drop in mpg?

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The colder weather naturally reduces MPG anyway. The colder air is more dense, which needs more fuel adding to the ratio to give the right bang.

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Yes, a poorly functioning fuel filter will cause a loss of m.p.g.

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It had a service about 4k miles ago so I would assume then.. however I will need to check to what exactly was done - could a blocked / clogged fuel filter provide a sudden drop in mpg?

Never assume anything.
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When was the fuel filter last changed ?

Havent we been here already today? Lol
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The colder weather naturally reduces MPG anyway. The colder air is more dense, which needs more fuel adding to the ratio to give the right bang.

Yes i understand this, however it hasn't really got cold yet and during the 2 winters I have owned the car for it hasn't noticably affected performance!

Never assume anything.

Sounds like a voice of experience...! I will check the log and come back to you later.

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Today & yesterday & so on & so forth . .

A million times Ian . . . we can almost predict the answers to the questions we are asking . . . :)

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I must admit, fuel filter is the best shout at the moment. I had mine changed a few days ago, it makes one heck of a difference. I would also suggest for best performance, replace the air filter too.

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The M.A.F. sensor is another potential culprit & is always worth a look & clean up if required

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  • 7 months later...

MAF sensor. What is it and where is it located please?

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  • 3 months later...

MAF Sensor - Mass Air Flow sensor, its in the housing to the air filter, where you see an electrical connector.

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