An experience with fault codes with my 2002 plus 8 with Gems. I had an Autel Maxiscan. The engine MIL light had come on. Maxiscan gave the reason as "random intermittent misfire". Car was running well and no misfires noticed. The system does a statistcal analysis that, when a trigger level is reached, creates a fault warning. I checked everything but it persisted occassionally. As a test I tried using V-Power higher octane fuel and the fault warning stopped. The Maxiscan was used to clear the faults. It also had a facility for live display while the engine was running. I couldn't spot any obvious reason for the misfires using this. Handy for checking many things. The car was running very well.
A later fault that showed up was a downline oxygen sensor one. Maxiscan determined a downstream sensor heater fault and live running showed which one it was, i.e. a post cat sensor on one side of the twin system.. Engine ran well as that sensor was effectively checking the cat. The pre-cat sensors were fine and the engine being managed well. Finding a replacement sensor....I took the faulty one out and contacted Rimmer Bros. They couldn't recognise the numbers on it. I went back to gomog and found part numbers in the Gems manual there. Bought from Rimmers using those as they recognised them and in stock. The old sensor was a bugger to remove! My go-to MOT garage used a good torch to heat it and remove for me.
