Consumption gone from 60mpg to 45mpg

[lebjos]

Hi all,

I always got great MPG with my Polo 1.2 - it would usually be around 55-65mpg depending on how I drive it.

However the past few weeks it's suddenly dropped to around 45mpg, any idea why this might be? Nothings changed and the car doesn't need a service...

I wondered if maybe the car was somehow connected to the internet, and knowing VW the 65mpg figure was not realistic and they somehow pushed an update to the car to make the consumption read more accurately lol

[d-ash]

Dodgy O2 sensors? The pre and post cat O2 (lambda) sensors control fuel mixture and can result in an increase in fuel usage of around 20% if faulty. However, if one had failed, the engine management warning light should have come on. Only replace if you need to; they cost £140 each plus fitting!!
Blocked air filter could also increase fuel usage, but if regularly serviced is unlikely cause.
First, it might be worth getting a VCDS readout to see if there are any error messages.