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Hey, I'm new here but I have a 2003 Jaguar XJ8 base model that had some work done for a misfire back in the beginning of 2025 and as a result of this I had my car's computer reset. I've been driving it ever since daily and my computer's monitors will not reset and it's been well after 500 miles by now. It's kind of urgent as I cannot get my car to pass NYS inspection and other than that, the car is in perfect condition so I'm a bit frustrated. Is anyone who's familiar with older XJ8s aware of or have any speculation on how to reset this drive cycle? I have no lights on, I just can't pass emissions. Thank you.
Thanks for the fast reply, although I've found that exact list before and on three separate occasions completed the check list to a tee. I'm wondering if I potentially have an ecu problem.
I have a 1998 x308 and never heard of this but what does interest me is how a test drive so comprehensive as this could be achieved without interference from other traffic, traffic lights etc unless it was done at great expense on a stationary dyno.
Last edited by DaveX01; Dec 1, 2025 at 01:52 PM.
Reason: spelling error
When monitors won't set it may be due to such as:
1. some required condition not met e.g. for Evap too much/little fuel
2. something marginal e.g. tired sensor
3. an error (e.g. a wire is broken so the PCM cannot retain learned values)
The drive cycle can help tell you what conditions must be met and also what kind of driving can speed up setting of monitors.
Any unset monitor is a hint about the kinds of things the car is unhappy about.
If #1 & #3 are OK then sometimes you can find a sensor which to the car is plausible but is wrong - worth checking any you understand (via OBD) and of course check your fuel trims, MAF readings and so on.
2003 XJ8 Drive Cycle
