Copied from Yaris/Vitz 2007 User Manual.
FOR VEHICLES EQUIPPED WITH CATALYTIC CONVERTER CAUTION:
If a large amount of unburned gasoline or gasoline
vapors flow into the converter, it may cause
overheating and create a fire hazard. To prevent this,
observe the following precautions.
(a) Use only unleaded gasoline.
(b) Avoid idling the engine for more than 20 minutes.
(c) Avoid performing unnecessary spark jump tests.
(1) Perform a spark jump test only when absolutely
necessary. Perform this test as rapidly as
(2) While testing, never race the engine.
(d) Avoid a prolonged engine compression
measurement. Engine compression measurements
must be performed as rapidly as possible.
(e) Do not run the engine when the fuel tank is nearly
empty. This may cause the engine to misfire and
create an extra load on the converter.