What does a temperature difference between the inlet and outlet of a catalytic converter indicate if it is less than expected?

A temperature difference between the inlet and outlet of a catalytic converter is an important indicator of its performance. When the temperature difference is less than expected, it suggests that the catalytic converter is not functioning effectively.

A catalytic converter works by facilitating chemical reactions that convert harmful exhaust gases into less harmful emissions. As this process occurs, the exhaust gases heat up as they pass through the converter. A significant temperature drop from the inlet to the outlet is expected because heat is released during these reactions.

If the temperature difference is minimal, it can indicate that the catalytic converter is either clogged, which prevents proper exhaust flow, or degraded, meaning the catalyst material is no longer effectively facilitating the reactions necessary for reducing emissions. This loss of efficiency can lead to increased harmful emissions and potentially cause issues within the engine or exhaust system.

Thus, a reduced temperature differential serves as a warning sign of potential problems, pointing towards issues with the catalytic converter's performance.