Auto Repair Help
Carl’s Corner – Auto Repair Help


By Carl O’Reilly

Exhaust fumes are present in the passenger compartment. The condition may be worse while the air conditioning or heater is on.

The usual cause of this symptom is an exhaust leak. Exhaust fumes can enter the passenger compartment from the heater and air conditioning vents.

An inspection of the exhaust system will be necessary. Focus your inspection on the exhaust manifold gaskets and the gaskets that attach the exhaust pipe to the manifold. If either of these gaskets are leaking, exhaust fumes can enter the passenger compartment. Inspect for broken or missing exhaust manifold bolts. Inspect the exhaust system beneath the vehicle for damage or leaks. Inspect the muffler and catalytic converter to ensure they are intact and leak free. Often, an exhaust leak will create a spitting sound when the engine is cold and will diminish after the engine has reached operating temperature. Pinpointing the leak when the engine is cold may be easier.

Once the source of the exhaust leak has been pinpointed, the exhaust system will have to be repaired.

You should use extreme caution when working around hot or rotating engine parts. If service to the exhaust manifold is required, it is recommended that the manifold bolts be sprayed with a penetrating oil prior to removal. Allowing the bolts to soak for 15 to 20 minutes will also aid in the removal. Work on the exhaust system should be performed when the engine is cold.

2 responses to “Diagnose Exhaust Fumes In Passenger Compartment”

  1. Typical Response says:

    Wow! Really. An article about with a title about diagnosing exhaust fumes in passenger compart actually has nothing about diagnosing exhaust fumes in passenger compartment. It just talks about finding an exhaust leak and maybe fixing it. Your article is a blatant waste of electrons.

  2. Anne Tennock says:

    We’ve had our whole exhaust system replaced and fumes are still coming in. We’ve also replaced the seal around the rear hatch door.

    The fumes are worst just outside the passenger door (really bad). The mechanic at the exhaust place said it might be something in the engine, but I can’t remember what.

    Suggestions welcomed.

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