Diesel engines producing black smoke is nothing new, but what happens when you get a check engine light illuminated with this? Live data, a lab scope, and a multimeter were used in this case to verify the fix when no obvious sign of the issue was found upon visual inspection.
Vehicle
2009 Mercedes-Benz Sprinter 2.2 Diesel
Title
Code 2078, Smoke Comes From Exhaust, Replaced Diesel Particulate Filter Pressure Sensor
Complaint
The customer states there is smoke coming from the exhaust. The customer also states the check engine light is on.
Cause
Confirmed the customer’s complaint and found smoke came from the exhaust. Connected a scan tool and found code 2078 – Particulate Filter Differential Pressure Sensor Maximum Exceeded. Performed a road test, used the scan tool to monitor live data and found the diesel particulate filter pressure sensor signal parameter was erratic. Performed a visual inspection of the diesel particulate filter pressure sensor and found no obvious faults. Using a lab scope, backprobed the diesel particulate filter pressure sensor signal circuit at the control module and found the signal parameter was erratic, which indicated there was a fault in the sensor or circuitry. Used a multi-meter to measure the resistance of the diesel particulate filter pressure sensor and found the measured resistance was out of specifications. These test results verified the diesel particulate filter pressure sensor was faulty.
Correction
Replaced the diesel particulate filter pressure sensor and verified the vehicle operated properly. The customer’s concern did not return.