Hi all i have a 2005 mk2 octavia 2.0tdi BKD dsg engine finally got it on vcds scan to see if any fault codes which there wasnt.The cars been recently serviced replace the fuel filter and air filters oil etc.Ive seen a few posts about regarding various sensors  having faults which could cause poor mpg return.Around town id say im getting around 25 and on a run 30 at a push ive copied and pasted the results which i received off the guy who scanned the car 

    Address 01: Engine  (03G 906 016 DS)

14:14:09 Group 007: Temperatures
  64.8°C  Fuel Temperature (G81)       
  34.2°C  Intake Air Temperature (G72)
  77.4°C  Coolant Temperature (G62)

14:14:09 Group 002: Idle Speed
  819 /min  Engine Speed (G28)
  0.0 %  Accel. Pedal Pos. Sensor 1 (G79)
   0 01  0  Operation Status 
  77.4°C  Coolant Temperature (G62)

14:14:09 Group 003: Exhaust Gas Recirculation (EGR)
  819 /min  Engine Speed (G28)
  250.0 mg/str  Exhaust Gas Recirculat. (spec.)
  15.0 mg/str  Exhaust Gas Recirculat. (actual)
  96.4 %  Exhaust Gas Recirc. Duty Cycle

 

If anyone has any advice would be great cheers Mick 

How are you measuring the MPG, from the maxidot or brim to brim refill mileage? The former can be quite a way out, usually optimistic but not always, it can also be changed by +/- 9% using VCDS.

 

What work had been done prior to the drop in economy? - Cam belt by any chance?

 

There is nothing to be gleaned from the live data printout.

Edited 25 July, 20214 yr by J.R.

Check your wheels are not getting hot after a run.

 

A sticking brake calliper will cause poor MPG, but not show in any fault scan.

Having had two Octys both 2.0 140bhp , this one with the CR engine, but both done 60mpg + on long runs and pulling caravan 35mpg. As now only doing small mileage get only 45 mpg around town .

On 26/07/2021 at 11:31, softscoop said:

Check your wheels are not getting hot after a run.

 

A sticking brake calliper will cause poor MPG, but not show in any fault scan.

 

I would second that. For some reason, it is usually the rears that have problems first, and it seems that it is an easy thing to overlook when confronted by all the electrickery that cars offer these days.

 

If checking wheel temperature by hand, be cautious because they could be very hot.

2 hours ago, Camlobe said:

For some reason, it is usually the rears that have problems first,

Because the main function of the back wheels on an FWD car is stopping the back bumper dragging on the ground. Practically no-one actually needs rear discs, but stylists think "they look better" (than drums).

Also check the MAF sensor as this controls the fueling as if it is out of spec it may cause the car to over fuel.