Home Articles Mercedes Diesel Engine Code – DPF Out of Range High

Mercedes Diesel Engine Code – DPF Out of Range High

This code is common with the MBE 900 Mercedes Diesel engine. It reads “DPF out of range high” which means the readings the engine control unit is receiving are out of the allowed limits. The 2 steel lines on the DPF measure air flow at the inlet and the outlet of the DPF which monitors the filter cartridge condition.

Using the diagnostic software is straight forward with a troubleshooting link at the bottom of the same page that the engine code is posted. All that has to be done is the code has to be highlighted and then the “troubleshoot code” link has to be clicked.

After this step a series of steps is presented and have to be followed to the letter to test the fault code circuit. In this case the voltage is checked automatically and if it is at the right voltage level the line at the outlet of the DPF must be checked and replaced if necessary.

Since the filter gets obstructed with soot from the engine the flow and temperature must be at certain parameters. When they are not it causes engine warning codes, a loss of engine power and eventually could damage the DPF. The amber engine light that illuminates is there to protect the system so it’s not a bad thing.

The emission system is not fail safe on these engines and has to be checked out once in a while for filter blockage. Using the diagnostic software is one way. The filter condition indicator in the DPF section goes from zero to three. Zero is clean while three is code red. The other way is the dash warning lights that will come on when the temperature or air flow at the DPF is out of range at the filter inlet and outlet.

One added maintenance procedure we have added to our fleet with these Mercedes engines is to perform a forced regen every oil change. This will be every 15,000 km to keep up with the soot build up and keep the filter in the DPF clean avoiding unexpected trouble down the road.

If you own an MBE 900 diesel let me know how they are performing for you and leave a comment below with any questions. New technology isn’t perfect but if we can stay on top of the problems by learning and doing the required diagnostics and repairs the wheels will keep on turning.