Misbehaving thermostat wasting fuel on an Audi A4 1.9 TDI (2007 – 153,209 miles)
β οΈ Thermostats are critical in maintaining the best fuel economy and lowest emissions for your vehicle. π Here’s a misbehaving one, unable to close properly, in an Audi A4 1.9 TDI (2007 – 153,209 miles). βΉοΈ This will cause poor fuel economy, higher emissions (some will fail MOT), increased noise