Smart Fortwo DPF Warning: Black Smoke & Power Loss

Had similar symptoms on a Smart Forfour CDI from 2005. The reduced power and black smoke pointed to DPF issues, specifically the exhaust back pressure sensor sending faulty readings. The low pressure readings were causing the engine management system to enter limp mode. A diagnostic scan confirmed the particulate filter was getting blocked and the pressure sensor was defective. The repair required replacing both the sensor and cleaning the DPF system. This is a relatively serious issue that needs prompt attention since: Continued driving risks damaging the DPF, Engine performance will keep declining, Fuel consumption increases significantly, Risk of complete DPF failure increases Key checks before visiting a garage: Get the error codes scanned, Check service history for previous DPF issues, Verify if the car has been used mainly for short trips, Look for visible damage around the exhaust system The repair involves specialized diagnostic equipment to properly test the back pressure readings. The symptoms match classic DPF system problems, so getting it checked soon is important to prevent more expensive repairs later.

Thanks for sharing those details about the DPF repair. The symptoms you described match exactly what I experienced with my Smart Fortwo. The emission control system warning and black smoke were quite worrying at first. After getting it fixed, the exhaust pressure normalized and all those issues cleared up completely. Since you went through a similar repair already, do you remember roughly what you paid for the pressure sensor replacement and DPF cleaning? Also curious if you had any related problems come up afterwards. From my experience, catching these exhaust system issues early really helps prevent bigger headaches later on.

Just had the repairs done last week actually. The faulty exhaust back pressure sensor was the main culprit, which cost 245€ to replace. Once fixed, the diesel exhaust pressure returned to normal and the engine regained full power. The mechanic confirmed the DPF was only partially blocked, so a proper cleaning was enough without needing a full replacement. The diagnostic tests showed the pressure readings are now within specs and the diesel engine is running smoothly again. No issues since the repair, black smoke is gone, no more warning lights, and power delivery is back to normal. The reduced power mode doesnt kick in anymore since the pressure sensor is working correctly. If your Smart is showing similar DPF issues, getting the exhaust pressure sensor checked first makes sense as its often the root cause. Much cheaper than replacing the entire particulate filter system.

Following up to share my repair experience: Finally had the Smart checked by a specialist workshop last week. The mechanic found both a faulty pressure sensor and partial DPF blockage. Total bill came to 580€, 260€ for the sensor plus labor, and 320€ for the DPF cleaning service. The emission control system is working perfectly now. No more black smoke, engine has full power again, and the exhaust smell is gone. The reduced power warning disappeared right after they fixed the pressure sensor. Really glad I caught the DPF issues early. The mechanic confirmed waiting longer could have meant complete filter failure and a much bigger repair bill. The diagnostic testing showed low pressure readings were indeed the root cause. They also gave the exhaust system a thorough inspection and found everything else was in good condition. Money well spent considering how smoothly the car runs now compared to before.