I have recently purchased a Citroen DS3 155THP. It had 48,000km on the clock and has gone for its annual service before i bought the car. Soon after an engin light came on and the car has gone into safe mode. I sent the car in and they had to tighten the timing chain. The car was running fine after that, however shortly after the cars thermostat did not want to go up. If i am stationary it goes up and then drops back down when i drive!!! And i can tell that my fuel consumption has increased as well. I presume this will require a new temp sensor.