2000 xj8 error code p1646. I a have just changed up stream o2 sensor,car ran for 10minuets.then engine light came on again same error code what am I doing wrong need help.... thank you in advance jrb53

 

The post is kinda short and is missing alot of info. You just changed WHAT UPSTREAM O2 Sensor???

The DTC is for the Bank 1 Sensor 1.
Did you change the right side upstream sensor???

Did you monitor the sensor after installation??

Do you have a wiring fault??

Do you have an ECM fault???

There is alot more to diagnostics than replacing a part.
Sometimes it's not the part that failed but connections to it.

bob gauff

 

I changed the right up steam sensor.the obd11 reader tells me it cannot read bank 1 so I could not monitor anything will have to take it to a shop to check the problem thanks for the advice...

 

If your OBD reader cannot read bank1 I would suspect a bad connection. I think all the O2 sensors connect to a block on the firewall behind the throttle body.
As Motorcarman said, to enable us to help you, we need more information.
History of the problem,
if restricted performance,
error codes, you gave P1646 which does not equate to O2 sensors.
People on the forum are friendly and helpful, they just need a few days to work through your problem.

 

the problem started when I had the transmisson replaced. I have had no other problems apart from check engine light and error code p1646.there has been no problems with performance. I changed bank 1 upper 02 sensor after reading on the forum that p1646 was the 02 sensor. the sensor is supposed to be the right one ie.walker heated 02 sensor direct fit from oxygensensors.com pre cat I am at a loss of what to do next.I can fix anything mechanical but am at a loss when it becomes electrical so I am stuck......so I would apprecate any help thanks

 

When they replaced the transmission its entirely possible they mixed the cables for the sensors and plugged the right sensor into the left cable etc, so check that to be sure,JJ

 

thanks I will try that in the morning

 

p1646 does not equate to o2 sensor? I was getting this error on my 1999 xj8 and I studied the threads and I have ordered a denso 234 9029 air fuel ratio sensor to replace the one I was lead to believe is bad. Upstream. right side. Am I wrong?

 

Hi Dav1dw1lson,

The DTC lists are available for download from this forum:

http://www.mediafire.com/?oc5ad7qbl2j6t#f51l3zghi1t39

It is important to consult the correct list for your model year and engine (AJ26 or AJ27), since P1646 indicates a different malfunction depending on the engine.

Cheers,

Don