Hi guys.
Ok probably a stupid question but should the MIL/Engine warning light light up when the ignition key is in turned to position 2 or when the engine is started and then extinguish?

Reason i ask is, that i have an intermittent ABS issue sometimes when starting out in the morning the ABS warning light kicks in either as soon as i start moving or very soon after and sometimes it is fine. Now i have had my 2001 X_Type 3.0 AWD for a year now and have been slowly getting rid of all the little annoyning issues it had when i bought it and i replaced all the ABS sensors and leads going to the hubs not long after i got it and this cured the initial intermittent ABS issue i had, but it has returned.

So i recently bought and OBD Diagnostics tool to connect to my X-Type and narrow down which wheel was triggering the ABS light on occasion (typically it hasn't triggered since i got the OBD code reader an Autel Maxiscan ms509 FYI).

But when i first connected the scanner to the Jag it came up showing P1646 & P1647 DTC codes! basically both heated O2 sensors upstream on banks 1 & 2. BUT my MIL light has never been on to indicate any issues?? So i cleared the codes and have had the car out for several drives now and the codes have never came back! "well that's good" i hear you say, But i did now just realise that the MIL light does not show up on my dash at all never, not even during start up and i'm wondering should it and if so why mine doesn't?

Has the bulb been removed to hide a previous issue during MOT testing (Car went through it's MOT this year without issues i might add not even any emissions problems) or does the MIL light not show at all until there is an issue and is there a way of testing to see is the MIL Light is working other than taking the dash apart to check 1 little bulb! Thanks for any advice in advance by the way i am in the UK.