Service Required On Dash flashing up.

[waynelondon]

Does anyone know what trips the service required on the dash is it time millage or trips.Mines is flashing up the message only when i switch the car on then it goes away after.I have booked it in for a service next week but was interested to know if anyone knows hows its triggered.?

[BrianG]

If it's a diesel XJ, and like the 2006 XJ 2.7 TDVi that I had for a while, then the 'service due' message is usually triggered by contaminated oil and/or too high an oil level, as there are monitors for these conditions. The cause is usually repeated incomplete forced DPF regeneration cycles, resulting from doing lots of short trips. The incomplete DPF regen results in excess diesel fuel getting into the sump oil and raising the level. If ignored it can rise until it gets to the point where the engine can burn its own sump oil and 'run away' un-stoppably and self destruct.

To prevent the possibility of run away and get rid of the service due message, on other forums some member advocate not filling the sump to the full mark on the dipstick after a service. This overlooks the fact that while the oil level is not high enough to trigger the message, dilution of the oil can still take place, with the consequent reduction in lubrication properties and risk to engine failure.

[waynelondon]

it had a service just under a year ago and has had the oil changed in the last 6 months.When the car went in for a DPF clean i got them to test the oil and they came back and said the oil was very good and no need to change until service time this was at my local Jag dealer Rockar.

[BrianG]

it had a service just under a year ago and has had the oil changed in the last 6 months.When the car went in for a DPF clean i got them to test the oil and they came back and said the oil was very good and no need to change until service time this was at my local Jag dealer Rockar.

Presumably you are not getting to 15,000 miles between annual services, which is why you had an oil change later when it reached the 15,000 interval - hope you got a filter change too. Your dealer may have only checked the oil for general colour from carbon build up, not diesel dilution.
Why did your car have to go in for a DPF clean? It should get driven enough to clean the DPF as you drive, unless you are doing too many town miles or too many short trips, which will then cause forced regeneration(s). I found the dipstick on the 2.7 was difficult to decide where 'max' actually was, i.e. above or below the top yellow plastic 'bobble'. If your dealer is like my main dealer they always filled the oil to just above the bobble on servicing. This could leave a very small margin for any excess diesel from forced DPF regeneration cycles to reach the critical level and then cause the service due message.

[waynelondon]

Yes the DPF was blocked and a message flashed up to seek dealer which i did.Wife fault keep going on about shopping trips which are short lol.Anyway i had the filter cleaned and i wanted a oil change but they told me they will test the oil and if it found to be bad they would change it but they said it was good and no change until the sevice.Again it is about a year since the last service was done in any case.