Exhaust system repairs are not expensive in general, but it also depends on your vehicle. Expect to pay between $100-$400.
The Cause of Leakage
Commonly, when you have a leak in the exhaust system, it is caused by a cracked exhaust manifold. The manifold takes the burned gases, which are essentially the burned fuel residue from the combustion process, from the engine and ejects it out through the tailpipe. Over time, this process of constant heating and cooling may cause the manifold to crack, and the leakage begins. In this case, the manifold should be replaced.
If the manifold is fine and the leakage exists, it could be caused by the breakage of a muffler, a catalytic converter, or a tailpipe (all of them could simply rust with time). The solution is same – broken parts should be replaced.
Some minor issues like broken mounting bolts, studs, or gaskets could be the cause of leakage too.
How Do You Know There’s a Leakage?
If there is no visible evidence of leakage, some collateral effects could indicate it. Firstly, your check engine light should be on. Secondly, you may experience strange loud noises from the engine or an odor of something burned or melted; the performance of such engine may be seriously reduced.
Is It Serious?
Not crucially serious, but it is better to repair the issue as soon as possible to protect other parts of the vehicle from melting and breaking.
The exact cost of exhaust system repair varies from vehicle to vehicle and from mechanic to mechanic. Some service providers like YourMechanic indicate the exact cost of repair for different vehicles online.