Rotten Egg Smell During Acceleration
A rotten egg (sulfur) smell when accelerating in a 2019 BMW 3 Series typically indicates a rich fuel mixture or a failing catalytic converter. The sulfur odor is caused by unburned fuel or hydrogen sulfide in the exhaust, which can damage the catalytic converter over time.
Diagnosis Details
Possible Causes
Failing catalytic converter – internal damage or clogging prevents proper conversion of exhaust gases, leading to sulfur smell.
Rich fuel mixture – faulty oxygen sensor, fuel injector leak, or mass airflow sensor causing excess fuel in the exhaust.
Fuel contamination – bad or high-sulfur fuel can produce the odor, especially under load.
Related OBD-II Codes
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What You Should Do
Check for diagnostic trouble codes using an OBD-II scanner.
Inspect the catalytic converter for damage or clogging.
Test oxygen sensor readings and fuel trim values.
Verify fuel quality and consider a fuel system cleaner.
If codes are present, address the root cause (e.g., replace O2 sensor, repair exhaust leak, or replace catalytic converter).
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Disclaimer: This AI-generated diagnosis is for informational reference only. Always consult a qualified mechanic for an in-person inspection. AutOwner is not responsible for decisions made based on this information.
