Canada - Exhaust System - Sulfur Smell

Bulletin
1212

Issue Date
2003-03-04

Reference
EM-03-001

Model
All Models

Year Range
All Model Years

Market
Canada

Component
EM, FU

Subject:
SULPHUR ODOUR/SMELL FROM EXHAUST

Some owners of Toyota vehicles may experience a sulphur-like or "rotten egg" odour from the exhaust system. High levels of sulphur in gasoline cause sulphur compounds to be deposited and burned off in the catalytic convertor during certain driving conditions.

Sulphur is a natural component of crude oil from which gasoline is refined and the amount of sulphur can be decreased through the refining process. amount of sulphur content in fuel sold in Canada can vary from Province to Province and varies considerably between gasoline brands.

On June 23, 1999, the federal government passed regulations limiting the amount of sulphur in gasoline. Starting in 2005, low-sulphur gasoline (that is gasoline with an average sulphur level of less than 30 ppm) is required throughout Canada. As an interim step, gasoline with an average sulphur level of not more than 150 ppm is required starting in 2002.

The implementation of the low-sulpur fuel requirement is not until January 2005. If customers are concerned about this issue they should contact Environment Canada, or their member of parliament.

APPLICABLE VEHICLES: All Models.

REPAIR PROCEDURE:
A sulphur emitted from the vehicle's tailpipe does not necessarily indicate that there is an issue with the engine's running condition, but is most likely directly related to the fuel. If the vehicle is exhibiting an excessive sulphur odour, the following checks should be performed:
- If the MIL light is ON, check for DTCs and repair as necessary.

If no trouble is found after performing the above check, recommend the customer try a different source of fuel.

NOTE:
Issue of this Technical Service Bulletin is to ensure that proper repair information is available. IT DOES NOT CONSTITUTE AN AUTHORIZATION FOR REPAIR. Normal provisions of the formal warranty policy, as applicable, will apply.

Regarding Sulphur Smell from Exhaust.
The following is provided to assist in handling customer inquiries on this topic.

1. Question: What is the cause of the "rotten egg" smell that I have experienced from my vehicle's exhaust?
Answer: The smell is caused by hydrogen sulfide in your exhaust. Hydrogen Sulfide is created from compounds of the sulphur in gasoline.

2. Question: I don't understand this. Isn't the gasoline burned in my engine?
Answer: Not all of the compounds in your fuel are burned. While today's engines run as efficiently as possible, unburned compounds are still passed through the exhaust to the catalytic converter. A chemical reaction in the converter can generate hydrogen sulfide under some driving conditions.

3. Question: I don't experience it all the time. Why is it worse when I stop at a red light?
Answer: It can be worse when you stop suddenly due to a rapid change in fuel mixture. A rapid change from lean to a rich fuel mixture on deceleration can briefly make the chemical reaction in your converter unstable, which generates more hydrogen sulfide.

4. Question: I didn't experience this with my last car. Why I am experiencing it now?
Answer: There can be several reasons for this. First of all, the catalytic converter on a new vehicle is operating at very high efficiency. Converters which have operated for a while are not as efficient and this reduces the condition to the point were no smell is noticed. You may have also purchased some fuel with a high sulphur content. Sulphur content in Canadian fuels is regulated but can still vary significantly and is generally much higher than in other markets. Driving style and conditions can also be a factor.

5. Question: I think that what I am experiencing is worse than normal. Should I take my vehicle to my dealer and have it checked?
Answer: Your dealer can check your vehicle. A problem with your fuel injection system's "fuel trim" could cause an excessively rich fuel mixture, which could make the condition worse. However, your vehicle's fuel management system is computerized and a problem is unlikely. We would recommend that you continue to drive your vehicle for a while. Even a slight drop in the efficiency of your converter as it breaks in can make a significant difference.

6. Question: What if it does not reduce?
Answer: We would also recommend that you try different gasoline brands. Lower sulphur content in the fuel will be evident in reducing the smell after 2-3 tanks. If you still feel there is a problem your dealer can check your vehicle's operation as discussed.

7. Question: Is this covered under my warranty?
Answer: The components in your engine management system and exhaust are covered for defects for 3 years or 60,000 km. On 2003 models the catalytic converter is covered for up to 8 years and 130,000km. Check your owner's manual supplement for details.

8. Question: What is Toyota doing about reducing sulphur in gasoline?
Answer: Toyota and other new vehicle manufacturers have been lobbying the federal government for some time to reduce sulphur levels in fuels sold in Canada. Fuel quality is a critical factor in ensuring that vehicles run efficiently with low emissions. They have reacted and have legislated that sulphur levels be reduced about 90% by 2005.

Some gasoline suppliers will phase this in sooner; so look for "clean fuel" promotion as one indication that low sulphur gas is being sold.