Freightliner chk eng code Dlp051

2010 Freightliner Columbia with Mercedes-benz engine runs rough about every 400 miles. Clears up after 75-90 miles. Chk eng lt comes on sometimes with code ECU 128 - Dlp 051 - Fail 02. Local dealer backed up until middle of next week!!!! Anyone know what this code is?

 

Turns out you are right.....sort of. It was the code for the throttle position sensor, but that was not the problem. Finally got truck into a dealer and they were able to determine the TPS sensor was faulting due to a throttle intake valve that was not opening/closing correctly. After replacing the valve and the CAC hose, the code cleared and everything was OK. Took less than 4 hours to diagnose and repair.

FYI I am seeing much better fuel mileage now and the engine seems to have more power at higher speeds. If this happens to anyone else I would definitely recommend getting into a dealer or GOOD service shop soon. You can continue to drive with this condition for 4-5K miles, but it will only get worse. This is not a check engine light to ignore.