What Can Cause Your Car to Smell Like Rotten Eggs?


It is not uncommon for your car to smell a little funky. If you are like most people, you are probably used to the smell of stale air coming out of your vents, or the aroma of engine oil and gasoline that lingers on your clothes after getting gas.

But there are some smells that are not quite as common—and they can be more than just a little, bit alarming. If your car starts to smell like rotten eggs, it could mean something serious is going on under the hood.
When your car smells like rotten eggs, it can be a sign of trouble! Not every case of a foul-smelling car is going to be a major problem, but it is always best to have it checked out by a professional.

What Causes It?

The most common cause of rotten egg smelling cars is the broken catalytic converter and the presence of hydrogen sulfide—which is what gives rotten eggs their distinctive scent. Hydrogen sulfide can come from any number of sources: the fuel system, the cooling system and even the exhaust system.
Major causes of rotten eggs smell in your car are:

  • A leakage or a broken catalytic converter, which converts pollutants into less harmful chemicals
  • A leak in the gas tank or fuel line
  • A problem with the coolant system (you may smell antifreeze)
  • Overuse of fuel additives such as octane boosters or ethanol mixes that contain alcohol (ethanol) or ethers (MTBE)
  • Low fuel levels in your vehicle's gas tank resulting in vaporized fuel entering your car through your engine's air intake (and then into your cabin)

There are also some more minor issues that could cause a foul odor: old fuel lines and dirty air filters are two common ones. If it is not too serious, they will just need cleaning out or replacing with new parts.

How Do You Fix It?

The first step is to determine whether the problem is serious enough for an immediate fix. If there are no other signs of trouble (such as smoke from beneath the hood or water in the oil), then it might be safe enough to wait until your next scheduled maintenance appointment before having any repairs made. However, if there are other signs it will be wise you get your checked by a profession immediately! If you need catalytic converter repair, give Prestige Auto Repair a call today!

4152 Mason Pointe Dr Mason, OH 45040 (513) 883-0504
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