Using a OBD II code scanner on my 4.6 P38a, I get the code P1187. This translates to "Oxygen sensor heater circuit short upstream". Ignore the upstream bit, just means the sensor before the cat. I can clear the code, on a hot start journey it doesn't come back, but does on a cold start. Guess the heater on the sensor is only energised when the coolant temp is low. Does anyone know if the car would still run in closed loop with this fault code? The check engine light is off. The car has done almost 100k and I doubt the sensors have been changed.
Alan C