HVAC Rotten Eggs Smell

[kerrton]

Quick question, I've been smelling intermittent, strong "rotten eggs" smell coming from my vents lately and now I'm almost positive it's not coming from outside.

It happens after driving at highway speeds and coming to a complete stop, for example at a red light immediately after entering a town from the highway. It normally happens when the A/C is on however today it happend with just the fan on, temp set to cold. A couple seconds after coming to a stop I smell a strong rotten egg propane or natural gas smell, it sustains itself for the duration of the red light, then as I take off it dissipates and disappears within 60 seconds. It won't do it every time, and it won't do it around town.

I know it sounds strange, which is exactly why I'm puzzled too. My first question is, does the R134a AC refridgerant have the "rotten eggs" additive? If so, I'm thinking there could be a leak, but this doesn't explain why I only smell it under very specific circumstances and the AC is still working just fine.

Any ideas would be appreciated.

[otto888man]

Have you tried to smell the exhaust after coming from the highway? It could be a bad or clogged air filter or bad plugs. How many kilometres on the Odo? I have a friend who has the same symptom we changed the plugs & got rid of the rotten egg smell. I hope this helps.

Otto

[kerrton]

Thanks for the ideas....I've only got 35,000 km on the car, it's like brand new.

A quick search of common troubleshooting guides indicate that a rotten egg smell could be pretty serious, such as:

a) catalytic converter problems
b) engine control module, fuel/air mixture problems or engine timing
c) bad fuel pressure regulator
d) vacuum leaks
e) engine compression issues

Not what I wanted to hear, but hopefully it's the cat conveter going bad, like I said the problem occurs rarely and only when coming to a stop from highway speeds. Good thing I've still got warranty for another year.

Any other ideas?

[pa2]

I've only got 35,000 km on the car, it's like brand new.

A quick search of common troubleshooting guides indicate that a rotten egg smell could be pretty serious, such as:

a) catalytic converter problems
b) engine control module, fuel/air mixture problems or engine timing
c) bad fuel pressure regulator
d) vacuum leaks
e) engine compression issues

Not what I wanted to hear, but hopefully it's the cat conveter going bad, like I said the problem occurs rarely and only when coming to a stop from highway speeds. Good thing I've still got warranty for another year.

Any other ideas?

Yep, And it could be the battery . Ever smell one that was over heating, just my guess.

[AZhitman]

99% certain it's a cat.

Get it to the dealer, and don't let them give you the car back until it's fixed.

[kerrton]

Thanks for input, I'll be taking it in right away.

I find it odd that it's so intermittent, and that I get such a strong dose of it through the air vents when stopped, I would think the rotten egg smell would mainly be apparent at the back of the vehicle near the tail pipe, can't quite figure out why such a strong persistent dose would blow in through the vents. Not good, considering I have a 2-year-old and a pregnant wife.

[kerrton]

Service manager said it can't be the cat because it would throw a code and the check engine light came on, he also gave me the standard advice of trying a different fuel supplier, check the cabin filter and I couldn't believe he said that this smell could be normal so try using the recirculate function, that one made me laugh.

I'm not so worried about the smell if it was just coming from the tailpipe, but it's not, it's coming in through the air vents.

Yesterday I got off the highway, came to stop with just the fan blowing and like every other time the strong rotten egg/propane smell started coming through the vents, so I jumped out and smelled the tailpipe exhaust - no rotten egg smell. It's only coming in through the air vents, and only after a highway trip and then coming to a complete stop.

Any ideas of where to start checking would be nice but I think I'm going to have to get more assertive and bring it back for a proper inspection.

[AZhitman]

I'd be taking it back and making the SM ride along.

Hell, you could have something dead in the HVAC plumbing, lol....

[kerrton]

If I hold the revs at around 3 or 4 thousand for 10 to 20 seconds in Park with just the fan on, no A/C, I get the faint odor too. Not as bad as when i come off the highway but it does occur. I'm going to have them go over the whole HVAC system and hopefully the can find something out of the ordinary.

Once again I seem to have a problem that no one else or a very select few owners may have, anyone else notice something like this? Maybe I'm just lucky, I'm going out to buy my Lotto ticket right now!!

[kerrton]

So it turns out that the exhaust is fine, no leaks, they figure some foreign material got on the exhaust and was burning off creating the smell. They disinfected and cleaned the heck out of everything and most importantly inspected the exhaust and determined there were no leaks.

[otto888man]

Its good to know that the problem has been fixed. Did you applied Rustproofing on your Rogue? That could be it.

[simonl]

is there anymore smell after the clean up?

[kerrton]

I haven't really checked to see if the smell is gone, honestly I don't think I want to know, I'm happier just assuming it's fixed for today and taking their word for it. They assured me that they tested it after all the work was done and the smell was gone, but honestly I'm not real confident in the fix. The reason being, they couldn't properly diagnose the problem before they moved ahead with the fix (i.e wash and disinfecte verything, including my immaculate engine compartment).

They guessed that there was something that spilled on the exhaust that was burning off, but couldn't really see anything abnormal. And even so, why did they disinfect my AC system and wash the engine bay if this was the problem, the fix doesn't fit the diagnosis. Also I haven't driven through anything that could cause a stink like that and if the spill came from the cars fluid then the source needs to be found and corrected. Also the smell was too consistent for me to believe that something was burning on the outside of the exhaust, I could replicate the smell at a precise set of circumstances for the past couple months and each time the smell and intensity of smell were identical, if something was burning off you would think it would decrease over time and eventually disappear. This was a very precise, rotten egg smell exactly like natural gas or propane, and the only thing on a vehicle that I know of that can make that smell is the catalytic converter, which they checked and assured me had no leaks so what more can I ask? If it does have a problem such as a pinhole leak I assume it will get worse over time and perhaps they can diagnose it then, but that could be years down the road still.

So like I said, for today I'm just assuming everything is fixed, fine and dandy! In the back of my mind I'm thinking about switching to a more experienced smaller garage, my Nissan dealer tries hard but they just don't seem to have the experience to solve many of these nagging issues, and throwing fixes at a problem that is not properly diagnosed is not a good way to do business, unless of course you want your customers to keep coming back time and time again for the same issue!

[paulvanharte]

i hope the cleaning fixed it, but when I read what they did I kind of laughed. Usually when there is the rotten egg smell, its the cat. Our Nissan Quest did it from day one. I complained and complained, never was fixed. They suggested changing fuel, maybe bad gas etc etc. They never agreed to replace the cat saying that it was fine. On occassion my Rogue will have a bit of a smell, but never that noticeable and only when driven hard.
Its my understanding the cat can do this even without any leaks, just the way the inside of the cat works when it gets hot.
I know for a fact it was the cat, because in my effort to get some power out of the 3 liter V6 I gutted the cat and the smell was gone. Only problem after driving the car for several years the lack of "cat" caused the computer to misfire the engine and I ended up replacing the cat and guess what, no smell with the replacement.
Good luck with this one.
Paul

[kerrton]

Paul, thanks so much for taking the time to post that, that was acutually more informative and reassuring than anything I got from Nissan service. I'm predicting I'm going to have an a similar issue as your Quest, but we'll see.

I can't figure out why a cat would produce a strong smell like that if it is a sealed unit, chemical reactions occur internally breaking down components such as sulfur compounds which in particular create a rotten egg smell. But how that smell escapes the cat without the presence of a leak is beyond me, but I'm not a mechanic. The other question I have is whether this "smell" has any dangers associated with it, I have 2-year-old daughter and a pregnant wife so even minute amounts of toxins are a concern to me. But I doubt anyone will be able to answer that for me, anyway thanks again everyone for the input.

[paulvanharte]

The smell actuall comes from the rear pipe. It may smell like its coming from the vents but I believe its either the cat itself or from the rear exhaust. Sometimes I smell it as well, but a lot of times it may come from cars in front of you, rather than your own car. With our Quest it would be so bad that you could smell it in the house after just parking it in the garage. Not sure about your other concern re health issues. Do a search on the web, maybe that will come up with something
Paul

[jmbones]

My wife's has the same smell every once in a while after just shut it off, definitely the cat. Ever get behind a vehicle on the hiway and smell it real bad? It's their cat as well...

[kerrton]

With the return of hot summer weather my stinky rotten egg smell has returned after coming to stop following a highway run. It's so bad that if i don't turn the AC fan off or switch to recirculate mode the whole cab immediately is filled with strong rotten egg stink.

There's a new service manager at my dealership and I haven't discussed the issue for a year, so perhaps there will be some new ideas and experience that will help get this fixed. I'm hoping someone else will have had the same issue addressed recently which they can use to guide them to a proper fix on my vehicle. I was wondering if perhaps it's related to fuel/air mixture but that doesn't explain why it only happens during hot highway trips.

[TaiLuu]

Clean The Evaporator With A/C Evaporator cleaner. 90% sure That Will cure the problem.

[kerrton]

In the heat of summer my exhaust is just as stinky as ever, so I took it to an exhaust expert for another opinion and they couldn't find any problem. All they could recommend was the standard "try another fuel provided" advice.

I can't be the only person with this problem, any other Rogue owners out there smell a strong rotten egg smell? It can be smelled from outside the car, or by turning on the fan drawing outside air into the cabin, and in my case the smell is overpowering.

[TaiLuu]

Better start checking those vents or the blower for a Dead animal. Until then, Febreze away ! ! !
I would really check that evaporator though.

[kerrton]

Thanks for the input, I did have the evaporator checked and the dealer gave me the full clean and disinfect treatment, but I knew this wasn't the issue. The HVAC air smells perfectly clean under most conditions, it's only when I get that exhaust really hot either by taking a highway trip in the summer heat or driving hard around town on a hot day, then the stink surrounds the car, you can smell it outside or if you turn on the fan the air that is sucked in when not in motion smells just like natural gas.

[Coyote676]

I hate to be that guy that registers on a forum and posts one thing on a 7 year old thread, but I'm losing my mind over here for the exact same reasons kerrton was. I've got a 370Z and am having the exact same sort of smell.

Every time I mention the cat to my service manager, I'm met with the same response that if it was going bad, the ECU would have thrown a code. The smell only pops up after putting the engine under load / driving it hard. Oddly enough, the more I put the car under load on a single driving session, the more the smell starts to dissipate. The first few times however smell just as awful as kerrton originally described.

Has anyone found anything that works regarding this issue? I'm continually told that its not the cats and I really don't want to roll the dice and replace them anyway if I don't have to. Have you guys seen the price on those things? Its ridiculous!

[itsa300zx]

My 2011 Rogue has this issue too. My wife says it only happens after using the AC, she does not drive the vehicle hard.