2001 Suburban exhaust odor

coetue

I have a new Suburban k1500 LT with only 250 miles. After the car has been running for 5+ minutes, the exhaust has a terrible sulfur smell, like rotten eggs. The smell happens whether or not the air conditioner / fan / heater is on. I love the car but the exhaust odor is unbearable. What could the cause be? Any suggestions?

spokane

You are correct that the sulfur odor is from the vehicle's exhaust system. It has nothing to do with heating and ventilation. This problem is associated with improper engine combustion which allows unburned fuel to go to the catalytic converter in the exhaust system. The odor results from a chemical reaction within the converter as the converter attempts, unsuccessfully, to do its job of cleaning up the exhaust gas stream. A small amount of odor is to be expected on some new vehicles but excessive odor indicates a problem with the engine's electronic combustion controls. Long-term operation in this mode wastes fuel, may be accompanied by poor engine performance, and damages both the converter and the air quality. If you believe the odor to be excessive but the dealer indicates it is normal, take a test drive in a similar vehicle (with similar mileage) so both you and the dealer's rep can make the comparison. Good luck.

coetue

Spokane, thanks for the useful post!
Is there a way for the dealer to test for a problem with the electronic combustion controls? Is this easily fixable? What if the dealer doesn't recognize the problem? So far, on the phone, the service manager said he's never encountered this before. I'm bringing it in next week. Thanks

spokane

Yes, Coetue, they certainly can connect the analyzer to your vehicle computer and check for faults, many types of which are logged in the vehicle computer and can thus be read by their equipment. This has a good chance of success but not every engine-control problem can be diagnosed and corrected in this way. Suggest that you also note and report any drivabilty irregularities. With so few miles, you can't have a very complete record of fuel economy but that information would also be valuable. Also note the degree of the odor following several miles at highway speeds as compared with the odor following a short in-town trip. If the odor continues to be distinct and you get the dreaded "nothing is wrong" report from the dealer, a tactful request to test drive another similar vehicle could provide the evidence that they need to take action. Lacking information from the analyzer, I would agree with them that it may be difficult to know what to do but they have technical guidance available from the manufacturer that goes beyond that from the diagnostic equipment. Most types of corrections for this sort of problem involve replacement of a sensor such as the exhaust oxygen-content sensor or a temperature sensor - these replacements are simple. It's very unlikely that your engine has any internal problem. Good luck.