Why is my S-Type suddenly using more fuel?

[Simpo Two]

For years it's averaged 26-27mpg, but now it's dropped to about 22mpg, and that's despite being recently serviced. Any ideas folks?

2001 3.0 SE, 146K miles.

[steve-p]

Nothing specific, but maybe it's overfuelling due to a dodgy sensor somewhere?

[Tame Technician]

When you say has now dropped, over what time period are we talking? We have seen so many people complaining or 3to5mpg drops since the beggining of the cold weather (December ish) upto now.

I know its sounds stupid, but cold weather can make 2 or 3 mpg drop off with absolutly nothing wrong with the car, for older higher milage cars (which I'm afrain yours is now John) 2 or 3 can become 4 or 5.

If its a more recent drop off than that, before you get into the posible engine management issues, just make sure none of the brakes are binding. Go for a blast to get them hot, pull up somewhere flat and see if you can push it and if, it should eaily rock back and forth, not consant resistance (not very scientific, but unless you have an access to an MOT spec brake tester or a two post ramp, its a good test)

[Simpo Two]

It seemed to happen quite quickly, I'd say during the cold snap, and the car did fail its MOT in January with binding brakes. However I'd noticed that the wheels seems unusually warm even last year when it was doing 'normal' mpg.

The weather is now warmer and the brakes have been fixed, but the mpg is still much lower than before. I'm selling it as soon as I find a replacement so it's not a major issue, it was just surprising.

[ronaldo342]

Have you checked the air filter and inlet ?, A tip as well I fitted a ramair filter and took out the old filter box, better on fuel and responds much better.

[NormanD]

Sounds like one of the O2 sensors on the CAT gone down

[Simpo Two]

Interesting - it was serviced only a couple of weeks ago by an independent I trust, and I hoped that would fix it. However the mpg seems the same. I might give him a call next week and see what he thinks. Thanks all.