Mercedes MBE 900 Diesel Engine Codes


Mercedes engine codes…..which ones have been the most common and how did we go about fixing them. I will talk about 3 of the most common engines codes to date. The one code I have seen the most over the years has been the ‘2631 Turbo Boost Performance’ the most common code with these MBE diesel engines. This code is literally a pain in the you know what primarily because it keeps coming back and in most cases does not take much to activate.

The main problem we found with the 2631 code was exhaust leaks and turbo boost leaks. If you’re going to tackle this fault then go as far as you can to repair the leaks until you’re satisfied that they have all been repaired. If you miss one the code will come back. The on board computer reads emission sensors and any variation from a preset parameter will cause a code to occur.

Mind you as a fleet operator if there is an exhaust leak or a boost leak I want to know. The turbo boost sensor sensitivity makes the computer side of the system far more accurate than the eyes and ears of a mechanic. The main objection to having an engine fault light on the dash is it has to be repaired soon. If not the problem gets worse and the driver usually does not like to run around with an amber engine code light on the dash.

Another code that has happened several times is the electrostatic oil separator which fills up and can’t do it’s job anymore. It separates liquids from vapors and recirculates the oil back to the crankcase and the vapors to the intake. A simple concept but when there is blockage the valve cover has to be replaced. Yes you read it the valve cover since the separator is integral with the valve cover assembly.

Yes it is expensive to buy ….you’re looking at about a thousand dollars. The emission system will suffer if you don’t change it so you need to bite the bullet and replace it. Out of range codes at the DPF are other problems that we’ve dealt with on a regular basis. All that’s happening is a pressure or temperature differential between the inlet and the outlet of the diesel particulate filter. Either the filter itself needs cleaning or a sensor or hose is faulty or plugged.

The key is to keep the emission system clean throughout the engine. Valves, sensors and filters have to be maintained with regular inspections and cleaning to avoid codes and diesel engine performance problems. Welcome to the twenty first century.