Replacing a catalytic converter is an expensive proposition, so keep an eye out for the signs of a clogged or dysfunctional cat to keep your car running right.

A check-engine light could be a gentle reminder or a sign of something catastrophic. We explain what a malfunction indicator light is and what you can do about it.

Is my catalytic converter sensor still bad? Do check engine lights turn off after a while? Or was the mechanic just looking for a $1,000 job? What do you think? — Russell ...

Continuing to drive once the check engine light is on raises the risk of increased vehicle emissions, reduced fuel economy, power loss, severe engine damage and vehicle breakdown.