The O2 sensor Bank 1 Sensor 2 on my Trajet 2 ltr GSI shows a heater circuit malfunction. Everything else is ok and the car runs perfectly. Clearing the fault works until I switch the engine off. When I start it up again the code shows and the EMS light comes on again. I have to assume the sensor is faulty. Which one of the two on the exhaust down pipe is it? The top or bottom one? Am I right in guessing it is the bottom one?