Skip the auto shop - Our mechanics make house calls

Q: Is there a smell which develops in a car when the catalytic converter starts to go bad?

asked by on

About one week ago, a strong unpleasant odor developed in my car. It just started one day; nothing I can think of was the cause. I had my local tire shop put the car up on their rack to inspect the underside chassis for maybe a small animal nest. Found nothing inside or out. A gas station attendant I use on a regular basis thought the smell (rotten eggs) might be the start of trouble with the catalytic converter. Any truth to that claim?

My car has 147500 miles.
My car has an automatic transmission.

Hi there. If there is a rotten egg or sulfur type of smell then most of the time this is caused by a failure in the catalytic converter. When these fail and become too hot they will smell like this. It needs to be tested with a temperature gun or with a back pressure tester. Both of these will help to identify this as the problem. A cylinder misfire will also cause this to occur. If you want to have this exhaust smell diagnosed, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair this.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Is there a smell which develops in a car when the catalytic converter starts to go bad?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car shakes and stalls when I press the accelerator.

Hello There, Shaking or vibration may be caused by many different things such as faulty spark plugs, poor fuel pressure or misfires. Other things such as a faulty idle air control valve may cause the engine idle to drop below...

Q: Why is my car overheating with coolant in the radiator, but not with water? It overheated today when i finally added coolant, why?

First of all the radiator cracks cannot be fixed with the sealer. It may work temporarily only until system pressure builds up and it will start leaking again. You are overheating now due to air pockets in the system and...

Q: Catalytic Converter 2004 Nissan Xterra

Hello - there are 4 catalytic converters for your vehicle with the V6 engine. There is one that is part of each exhaust manifold (that's 2), and one for each exhaust pipe just below the exhaust manifold (2 more). Space...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...