After a recent hard driving session I got MIL and a P1646. No restricted performance, nothing noticeable changed. Also if you deleted the code it would not illuminate again until next startup.
All good and well, not the first time I get a trouble code.
Things got a little more hairy when I opened my X308 workshop manual to troubleshoot the code and found that the P1646 is a secondary fuel pump relay issue, pertinent only to the supercharged version. Mine is the non-supercharged 4.0 V8, I don’t believe I have a secondary pump. So, what’s happening here?
I’ve red reports of the same code being used as a pass side upstream O2 sensor, but no mention of that in my manual. Is the info reliable? Don’t want to be forking out for a new sensor, let alone going through the pain of removing old one etc. if the one I got is good.