pleas help very poor mpg

[kingy38]

happy new year everyone.

i have a alhambra 1.9tdi 115bhp auy engine. 186000 with almost full history. but im now getting low mpg and i worked it out to be around 36mpg. tyres are all good,air filter clean,oil is ok, what else can i checked please.
there was a lot of white smoke this morning (very cold morning). can i disconnect aux heater ?
im stuck as to what to check next plus im very low on cash after buying new rear caliper on this wednesday as its leaking

please help guys

thanks

[Crasher]

The aux heater can use a lot of fuel, sometimes as much as 10mpg in slow traffic when very cold. You can disable it if you have some winter woollies.

[kingy38]

thanks for the reply mate, i drive alot and do all the school runs so mpg is important but so is warmth lol, is it worth doing a glow plug change ?

[Overdose]

I'm not far from Tavy and could help out at some point, but for now it seems like the engine is overfuelling. Won't be glow plugs as these are only used for starting.

Any sensor that has an input as a consideration for fuelling calculation can have an effect. Even something as simple as water temperature sender.

I had a Galaxy and usually got in the late 40's mpg, low 50s if on a long run, so you definitely seem to be using more fuel than what would be considered normal.

[kingy38]

hello mate, i replaced the coolant temp sensor a few months ago, i got the better one from eurocar parts. its been running fine up to now. last few weeks have been very thirsty for the old girl. where abouts you at ?
thanks for the reply

[Overdose]

Between Callington and Liskeard

[kingy38]

thats not far mate

[Crasher]

You need to do a full code read, print and clear and then drive it again watching the coolant temperature display as the car is driven along to make sure it does not start to dip significantly as you are driving along in the cruise, then do a code read again maybe a day or three later. This should give you an idea if the aux heater glow plug or thermostat needs replacing.

[kingy38]

the temp stays bang in the middle and does'nt seem to move, but i did a scan and got p1144 and cleared it but came straight back. i know its the maf sensor open circuit or ground . not sure
thanks

[Crasher]

Ignore VAG temperature gauges, their readings are complete nonsense just design to stop people fretting about the readings, give a man a gauge and he will worry about it. I have monitored the actual engine temp as being 72 when the gauge says 90 and the gauge still says 90 at a real 117... The real reading is shown is measuring blocks and you can use a graph trace to make the display easier to follow.