Hi all

I have a 2006 X type 2.1l V6 petrol. Showed a P1647 fault a couple of weeks after buying, and after filling up with gas. Replaced the upstream O2 sensor. Code cleared and CEL goes off for the duration of the trip but reappears shortly after startup. Any suggestions? I'm wondering if a hard reset of the ECU will do the trick

 

Unfortunately, I think you will need to replace the sensor again. The car is quite fussy about which brand of sensors are used. If the resistance of the heater is too low or high this fault will flag after a few trips. The heater in the sensor is only used when the engine is cold. I am not sure about the low end but anything above 5 Ohm will illuminate the light after a while. If you want to check it is the two black wires.
If you have used a Jaguar or a Denso sensor ignore this post.
The light will go out on its own after a few trips if the problem is rectified. No need for a scanner.

 

Thanks. It was a Denso sensor. Maybe it just needs a longer trip? Only really been doing short trips since replacing

 

There is the possibility that the old sensor blew the fuse. I don't know which one offhand.

 

The O2 sensor fuses are 38 and 42 in the engine compartment fuse block

 

Replaced the fuses, no joy. CEL still comes on shortly after start, clear the code, CEL stays off for duration of trip. Start up again, Groundhog day. Going to try a hard rest of the ECU, will report back

 

This code will only set when the engine is cold. It's a pretty simple circuit. When the ignition is on, the power goes through the fuse to one of the black wires on the connector. The other is shorted to ground through the ECU, depending on engine temperature. A definitive check is to connect a lightbulb between the two black wires in place of the sensor heater. When the engine is cold it should stay on or flash.

 

do you have a p1000 code

 

Bound to have P1000 as OP has been clearing the codes. BTW stop doing that!

 

Yes have a P1000, and yes, refraining from clearing

 

Ok, then after a bit most OBD monitors should set (if all do you get P1111 and all is good, don't clear anything!).

Then see which have not set and someone can probably suggest what to do.