BMW, Mercedes-Benz Warning Message
“Exhaust System Malfunction”
A fault has been detected in the exhaust aftertreatment system. On diesel models, this typically indicates DPF (diesel particulate filter) regeneration failure or SCR catalyst issues.
moderate severity
Common Causes
- DPF clogging from short-trip driving
- SCR catalyst efficiency below threshold
- Exhaust pressure sensor failure
- NOx sensor malfunction
- Exhaust gas temperature sensor fault
Immediate Action
For diesel models, attempt a highway regeneration drive (20+ minutes at sustained speed). If the message persists, schedule service to avoid DPF replacement.
Typical Repair Cost
$500–$4,000