Evaporative Emission Control Canister: Description and Operation

TWIN CANISTER SYSTEM
In the USA, to comply with evaporative emissions and On-board Diagnostics legislation, a number of XJ6 Sedans constituting 20% of annual Sedan sales have a twin canister evaporative loss control system. The twin canister system provides further reductions in evaporative emissions and enables the Engine Control Module (ECM) to test for leaks equivalent to a hole of 1 mm (0.040in.) diameter minimum.

A second carbon canister is added to reduce the concentration of fuel in the vapor that vents to atmosphere. It is installed under the right rear seat pan and connected in series with the first canister.