sounds like an exhaust leak, or a fuel leak. that depends on the smell.
The cause of cabin fumes on my VW was a breach in the CRANKCASE VENTILATION system.Brittle plastic connections and or tubing failure allows vaporized emissions to pass virtually unobstructed from engine-bay through cabin-air intake. There was also excessive oil leak visibal near filter-housing.
two things, exhaust has a leak of gases or fuel leak from engine bay
The primary cause of gas fumes in a Ford Expedition is a leak in the gas tank or vent. This allows fuel vapors to enter the cabin and poses many health risks.
Smelling engine fumes from your Corsa CDTI could indicate a potential issue with the exhaust system, such as a leak in the exhaust manifold or a damaged catalytic converter. It might also suggest problems with the engine's fuel system, leading to incomplete combustion. Additionally, a failing gasket or seal could allow fumes to enter the cabin. It's advisable to have the vehicle inspected by a mechanic to diagnose and address the issue promptly for safety and performance reasons.
A manifold leak is usually in reference to a failure of the intake manifold gasket. It can leak air, oil or coolant. It can leak to the outside of the engine or internally into the engine. A manifold leak may also refer to the Exhaust manifold that is leaking exhaust fumes from a bad gasket or a crack in the manifold.
a lot of things mostly a leak of some kind
is there any odor..??/ a small leak in the heater core will allow glycol fumes into the cabin.....this would smell sweet.
If exhuast leak exists at manifold or front pipe the fumes will usually be blown away when the car is moving (unless a fresh air vent is open) but when standing fumes more likely to find way into cab.
The first thing to look for would be an exhaust leak. Check for a fuel leak on the top of the engine.
power steering fluid
If your car smells like gas when you turn on the heater, it could indicate a fuel leak in the engine or fuel system. The heater draws air from the engine compartment, and if there's a leak, the gas fumes can be pulled into the cabin. Additionally, a malfunctioning fuel injector or a damaged fuel line might contribute to the odor. It's crucial to address this issue immediately, as it can be a fire hazard.