Our '92 Toyota Previus, which we just bought as is, has failed the Ontario Emissions Testing and therefore is not able to be plated. It passed safety with no problems, but due to a small leak in the exhaust pipe at the catalytic converter, the catalytic converter was replaced prior to the first emission testing because the mechanic stated that they would automatically fail the emission tests because of this leak.
After failing the first emission test, I took the van to another mechanic who examined the vehicle and found that the Air Filter was completely clogged. The plugs and wires seemed to be in good shape, and he couldn't find anything else that could be causing the failures without doing a thorough diagnostic. The air filter was replaced, and gas line anti-freeze was added into the gas. The van was then taken for a 30 minute highway run prior to being tested again. Although the results were greatly reduced, and it only failed 2 tests as opposed to 4 previously, the van still failed.
The product, Guarantee Emission Pass was added to the fuel and the van was driven almost 400km on the highway before being tested once again, this time at another place. The van failed 3 tests this time, and the ratings were once again high.
Any suggestions as to what could be wrong before I spend the money for an emission diagnostic test? In doing an internet search I came across a note that recommended replacing the oxygen sensor when replacing the catalytic convertor, but this was not done when the mechanic replaced the convertor. I plan to call the mechanic to ask why this would not have been done when it is highly recommended, but hopefully others may be able to make other suggestions for checking.
BTW, the van is automatic with 230,000km, and the A/C is not working. Other than this the van runs excellently and seems to be in great condition.
Thanks! Tim