Changing Bank 1 sensor 1 P1646

[aerophil]

I have recently bought a tidy 2002 2.1 X Type SE.  I now have everything working and she has tidied up nicely. It does have one fault that needs to be addressed. I have the Engine light on and the readout from the scanner is P1646.  I understand that this relates to Bank 1 sensor 1, again I believe that this is the upstream sensor on the firewall side and is located in the exhaust manifold.

 

I am getting conflicting info as to how to change it. Some insist that it can be replaced from below, others are equally adamant that the inlet manifold has to be removed to get to it.  My question is has anyone actually replaced this one.

 

best regards Phil

[aerophil]

Just thought I would give a quick update.  I replaced the sensor today an managed to fit it from the top. removing the screen cowl made its a bit easier but job done, no light

[aerophil]

So car drove really well this morning for about 30 miles and yes you guessed it, light came on.  Also noticed that the tickover has now climbed to 1200rpm

 

Any ideas.

[aerophil]

So did another scan today and it says P1000.  I deleted the code and the car now drives better than it has since ive had the car.. Looked up the code and it relates to an OBD drive cycle being incomplete. I presume that that light will probably come on again some point, when it does I will follow the instructions to complete the cycle. Hopefully I am getting somwhere.