Emissions System service does anyone know what to do

[warbler]

My Y reg V70 2.4 has a dashboard message telling me the emission system requires a service. What does this entail? I had it mot'd last month and the emissions were ok?

[aquabee]

You will have to get your codes read but a wild hunch would suggest your pre cat lambda sensor.These usually go around the 100k mark,but this is just a guide.I have a 2001 2.4 n/a v70 and Ive just replaced mine for exactly the same thing! Good luck!

Will