marathoner65

Basics: I am original owner of a 2003 HCH (CVT) w/126K mi. Overall it's been a great car. Had IMA pack replaced under warranty at 78K. I've kept up with all service intervals and service notices/recalls.

Problem: On and off for almost entire life of car we have noticed a rotten egg odor when stopping usually when engine is cold. This has gotten worse in the last 6 mos or so.

The car is not showing the CEL light and thus no error codes to read.

Based on reading I've done here and elsewhere, this could be everything from a bad cat convertor, one or more bad O2 sensors, a bad battery (12v or IMA) to a dead animal somewhere in (or near) the vehicle.

I'm wondering if anyone here has had the same or similar symptoms with their HCH of same or similar model year and if there are any recommended approaches to remediating the rotten egg odor.

From my experience, this seems to clearly be a tailpipe emissions issue. Fuel mix too rich?

Based on reading, I'm thinking about changing the primary (of 3) O2 sensors as a next step. Not happy about the >$200 price for that part (pn 36532-PZA-L01) though when I am not certain that will help.

I'd be most grateful for any feedback from the group.

ezone

No codes? I would not worry about it unless or until related codes have set.

It could be due to things far beyond your control such as the amount of sulfur in the fuel you are using.

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Make sure it's not the 12v battery you smell.

Make sure the trunk seal is not leaking, as something like that could be allowing exhaust to enter the trunk and cabin.

Make sure you aren't smelling the traffic in front of you.

marathoner65

ezone: No codes? I would not worry about it unless or until related codes have set.

Not too worried. Just the bad odor is really bugging my kids. We only smell it when we are stopped, open door and exit car---eg in morning when I am dropping them at school.

ezone: It could be due to things far beyond your control such as the amount of sulfur in the fuel you are using.

Good point. I may try fuel from another station for a month or two.

ezone: Make sure it's not the 12v battery you smell.

Just replaced the 12v battery in past 2 mos and still getting the odor.

ezone: Make sure the trunk seal is not leaking, as something like that could be allowing exhaust to enter the trunk and cabin.

No odor when we are in the car---unless we are stopped and open a door.

ezone: Make sure you aren't smelling the traffic in front of you.


Unlikely seeing we notice it mostly at school drop-off and any number of cars are in front of us.

I promised the kids I'd look into fixing it, but it might be "beyond our control".

If I were to try the primary O2 sensor, do I have to use the Honda (>$200) part, or is there another less expensive version that would do the trick?

ezone

You don't have to go through a Honda dealer, but I strongly recommend you stick with the original brand of sensor.

Find the brand name on the sensor (it will be DENSO or NTK)...and you might have to remove it and use a wire wheel to find the brand name, then go to that manufacturers website and use their lookup to obtain a part number for your particular application.
Then search for that part number.


EDIT: Your primary sensor is not a plain O2 sensor, it is an A/F sensor (sometimes called air-fuel ratio or wideband sensor), that's why it is not cheap.
According to the Honda parts catalog, California emission spec cars use one part number, 49 state cars use a different part number.


Brand name example---before and after using a wire wheel to remove rust, this NTK sensor was marked near the hex but I have seen brand names on the upper metal shell too:

Wankenstein

Possibly a cracked exhaust manifold. I purchased my first (of two) 6th gen Civic four years ago and it had a crack in the manifold that emitted a rotten eggs/sulfur smell and did not throw a CEL. After replacement smell was gone.
Here's a post (not a Civic) that may help: http://www.torontomazda3.ca/forum/sh...Egg-Smell-BARF! includes possibilities that Ezone mentioned.

The other possibilty is this (lol):

marathoner65

Thanks for feedback. Will look into checking exact O2 sensor as suggested as well as the possible cracked exhaust manifold.

Regarding exhaust manifold, I'll do some digging on ways to confirm/diagnose that situation. Any suggestions (visual inspection, etc.) on how to do that would be most appreciated.

Thank you!

ezone

Raw exhaust smell in the engine compartment upon startup would be the most obvious clue, and loud snapping noises.

Raw exhaust doesn't smell like rotten eggs to me either. That happens inside the cat.




However, IMO the engine used in the Hybrids did not have huge problems with exhaust manifolds like the D17 engine (and some others) do.