Mystery code
The engine management light has come on in my 2004 Jaguar X-TYPE 2.5 V6 petrol automatic, leaving the fault code ‘P1647’. I reset the fault code using a code reader, but it reappeared at the next cold start. Can you advise what the fault is likely to be and whether a DIY repair is possible? If not, what would be a reasonable price for an independent garage to complete the work? Steven Jones The code ‘P1647’ refers to ‘heated oxygen sensor (HO2S) 1 (upstream), bank 2 – control circuit malfunction’. It could be that the sensor has failed or there is a wiring fault.
The upstream sensor is the one in the manifold before the catalytic converter, and ‘bank 2’ indicates that it is the front bank nearest to the radiator. Access is obtained by removing the air filter box – once this is out of the way, the sensor should be readily visible. The wire from the sensor goes to a plug connected at the side of the battery box, so I would first check this to ensure the contacts are good. If the sensor does need to be replaced, it may be tight, and soaking it with a penetrating fluid beforehand may help. It will also be easier to remove if the engine is warm, but do take care not to burn yourself on the hot manifold.
The book time for the job of replacing the 02 sensor is 0.4 hours, but it would be reasonable for a garage to charge an hour’s labour as the job may be more involved if the sensor does not budge easily. If you carry out the job yourself you will need a 22mm 02 removal socket – this has a notch in the side to allow the socket to be fitted onto the sensor without damaging the wire. Often it is easier to cut the wire when removing the old sensor and using the 02 socket only for fitting the new unit, because a tight sensor may cause the socket to open up when trying to undo it.
The socket costs around £15 from Halfords (http://bit.ly/2cmlo2i) and the sensor is £102.09 from Autosessive (http://bit.ly/2cmio2j). I would expect an independent garage to be carry out the complete job for less than £200.