[dillo2k10]

My car has started to smell really bad, it smells like rotten egg but it's very strong outside the car . . . It's a 2001 1.6 ford focus
I had my cat and some exhaust parts and lambda sensors replaced few weeks ago if they could cause it .

Does anyone have any idea what it could be?

[Rochey18]

Inside the car I would of said your pollen filter.
Outside usually from your cat, hopefully someone has the answer.

[minty247]

dodgy cat i'd say

[Nissan doctor]

What caused the cat and sensors to fail do you know?

The rotten egg smell is a cat issue, normally caused by unburned fuel(sulphur) getting into the exhaust system. This may indicate another issue which could have been the cause of the your previous cat failure.

[johnthemull]

hydrogen sulphide.
your cat is bollixed

[Bullseye1]

Head gasket? Water from inside the exhaust system?

[antodeco]

Has to be the cat. It's either blocked or just not working

[vectra]

What exactly do people mean with the replies say it is not working?
I always assumed if the cat was gone then the car would not run properly?

[DoneDL]

Have the battery checked, had the same issue and that was the cause.

[worc]

Originally Posted by DoneDL

Have the battery checked, had the same issue and that was the cause.

Had the same nasty smell with a car once and it was the battery. Didn't sort it for a few days (what a tool ) and all the electrics blew because of it - cost the price of the car itself to sort.

[Nissan doctor]

Originally Posted by vectra

What exactly do people mean with the replies say it is not working?
I always assumed if the cat was gone then the car would not run properly?

If the cat is blocked then it won't run properly, if its not functioning for any other reason then the car may run fine, just use more fuel/throw an EML etc

[vectra]

Originally Posted by Nissan doctor

If the cat is blocked then it won't run properly, if its not functioning for any other reason then the car may run fine, just use more fuel/throw an EML etc

Was just wondering that as the Mondeo I had would smell stink of eggs If I gave it a good run, Car seemed to run fine though I did find it liked Loved Petrol.
Then I had a funny issue with starting at times. Engine would turn over but fail to fire until I turn off the key and try again at which point it would start instantly.
Maybe the cat was shagged but then again it flew through the NCT,
She was 02. I bought it in 05 and NCT'd in 06 @ 35k miles.

[Nissan doctor]

Originally Posted by vectra

Was just wondering that as the Mondeo I had would smell stink of eggs If I gave it a good run, Car seemed to run fine though I did find it liked Loved Petrol.
Then I had a funny issue with starting at times. Engine would turn over but fail to fire until I turn off the key and try again at which point it would start instantly.
Maybe the cat was shagged but then again it flew through the NCT,
She was 02. I bought it in 05 and NCT'd in 06 @ 35k miles.

The smell is not a fault with the cat its self, its cause by unburned fuel ending up in the cat, normally caused by a misfire/timing issue. This in turn damages the cat.

Cat failures are a symptom of a combustion problem, so in the OP's case, its likely that whatever problem caused the first cat to fail hasn't been properly diagnosed and repaired and is now effecting the new cat.


@OP, did you have your timing belt done in the weeks/months leading up to the original cat failure?