I've retrieved DTC P1646 - O2 sensor bank 1 sensor 1 on my 51reg 2.5L X type. I have my car serviced at the local Ford garage and they cannot remove the sensor (seized/corroded into manifold). They've given my an open ended bill for fixing this since they have no idea how long it will take (or how) to finally remove it!
Does anyone have any experience on this? Any tips or methods to help remove? The garage say they have given it a good soak in WD40 but still no good.
WD40 is ok but you really need some proper penetrating oil (plusgas for example) Give it a spray twice a day for a few days and let it soak in. Heat will be required as well so a blowtorch or heat gun. Heat the pipe, not the sensor and work the bolt back and forth. Good luck.