Yesterday my check engine light on my 2002 4.0 XK8 came on. Run a scan and came up with the code P1646. After researching, the code tell me a defective fuel pump 2 relay. Later models supposed to be a O2 sensor. Went to check the relay and it seems to have vanished. There is a missing slot where it is supposed to be. Cannot see any empty connectors either. Anyone have any idea where it might have vacated to? I have attached 2 pics as to where it is supposed to be.

 

The XK8 only has the one pump the R has a second one.

 

In some N/A Cars P1646 means:

ECM HO2S control malfunction –
A bank, upstream

IE A Oxygen Sensor /wiring/ECM problem,

 

Thanks guys. Prior to posting I searched a lot of threads and it seems as everyone has different ideas about this code. So I'm guessing that it's the O2 sensor, upstream on the drivers side (left). Found OEM part # LNE1684BB. Bit pricey, between 225 and 250, for a O2 sensor. Going to try it and hope it works. Car still seems to run great, no apparent difference in idle or driving.

 

Might be wise to check the wiring first?

 

Thanks Norri, I will do that. I only have 72k on the car and seems the sensor should last a bit longer. Sensors that I have had to replace on other cars have all had over 100k on them.

 

I think the O2S Sensor in question is on the A Bank: Passenger Side (US)

 

Thanks Paul, your right. The first threat I read said it was on the drivers side, but after more research people said it was on bank 1 or A. More research told me that 1, or A was on the passengers or right side. I did check the wiring and it looked good. I've ordered one and will take the old one out tonight after it cools down. 101 degrees here now.