Mercedes MBE 900 Diesel Engine Emission Code dpf out of range high

This code we're working on is a "DPF out of range high" on a Mercedes MBE 900 Diesel Engine. What triggers this code is a pressure differential between the inlet and outlet of the diesel particulate filter cartridge. In the video you can see the clamps on the outside of the muffler that can be removed allowing the cartridge to be removed for cleaning.

There are several shops in town that will do a cleaning of these cartridges. It's a two step process depending on how badly the blockage is. When using detroit diesel diagnostic software you can go in and see what range the filter is running at. It's 0 to 4 range with four being severe. Once the engine control module detects blockage it will run a regen while the engine is in service.

 In a perfect world that's all the emission system would need to do running regenerations to keep operating without any trouble. The DPF amber dash light illuminates when the regen process is taking place. There is no worries if it flashes on and off indicating a normal function instigated by the engine on board computer.

Mercedes calls the engine computer an MCM (motor control module). When hooked up with the laptop and software the tech can find the code and click on the "troubleshoot code" button at the bottom of the screen. This directs you to a step by step process to check one thing at a time then moving on to the next step. In this case the outlet braided pressure hose that reads outlet exhaust pressure of the filter cartridge has to be removed and tested for blockage.

It could be blocked with soot and ash build up and the best thing to do is replace it. This fault was cured replacing the hose. If it did not help the filter cartridge may be plugged up so a forced regen is a good idea. Eventually over time the filter cartridge needs to be serviced or replaced. Mercedes recommends servicing at 125,000 km or 75,000 miles.

We have 18 of these diesel engines in our fleet and have a good deal of experience which is your basic "hands on" experience that is of course the best teacher.

Mechanics & Diesel Engine Technology DPF out of range high engine code

The days a Mechanic can get out his screwdriver and tweek a diesel engine are gone. Yes it's 2012 and times have changed. 2007 was a year I won't forget. Emissions on diesel engines were fully operational and ready to provide us with cleaner air. I totally agree with this mandate but new technology has created a lot of headaches for us old school Mechanics who just want to fix the problem and never have to fix the same problem again.

If an engine farts the wrong way an engine code pops up. The parameters are strung as tight as a piano string so a minimal buildup of soot or carbon within the exhaust system and you're in for a challenge. However if you have the laptop, software and experience it gets easier. That's the good news....the unfortunate part is you'll need deep pockets to keep your engine fine tuned and code free.

We just had our first run with one of our 2007 Mercedes MBE diesel engines that just ran out of warranty. All this new terminology I'm going to tell you about is focused around  the muffler. The code was "DPF out of range high". This means the temperature or pressure at the sensors were not in their acceptable ranges. They are located right at the DPF "diesel particulate filter" (muffler) and tell the computer that there is a blockage starting to accumulate in the dpf cartridge/filter.

The on-board computer monitors this system and carries out automatic regenerations as it sees fit. A regen heats up the exhaust system to high temperatures and cooks the particulates out of the exhaust system without contaminating the environment. This works great and will give you trouble free driving for quite a while, however over time the regeneration process needs to be forced using your laptop software with the Mercedes MBE 900 diesels.

This is easy to do and can be done every second oil change or when required according to how hard the engine is worked. The longer it runs at operating temperature the better, because of the constant heat there will be less build up of particulates.

So getting back to our problem we checked the software for the last time the cartridge was serviced and it had been done once. It was not replaced but cleaned out 2 years earlier. By the way when you service the cartridge you must enter the details into the engine software records. So we replaced the cartridge which can easily be done on the bus by removing 2 clamps. It comes with gaskets as well.

Once the codes were deleted and the bus was road tested it came back clean and we were elated that everything worked out OK. So now we know what to do with that particular code, check the wiring, make sure you're getting a 0-5 Volt signal to the sensors and service or replace the DPF the cartridge. Recommended cleaning or replacement  is 150,000 km. for this particular Mercedes diesel engine. If you've had some experience with this please leave a comment :)