I would strongly suggest a forced regeneration with that 1409. I had to do it to mine again a few months ago with an error in the same range group. A common problem with them is DPF gets clogged, the DPF sensor starts going intermittent kicking it into limp mode. Then you got the intermittent burst of soot clogging up the exhaust because the car is not auto re-generating and wont do because there are other slight errors still present. Or the regeneration will start then due to the dpf already loading intermittent bits of soot into the exhaust at high pressure when its not totally burnt. This likes to mess up your o2 sensors aswell. The soot is forced thru because its got nowhere to go . So the O2 sensor works with the MAF and air side but also the EGR has to open and close at the right times. What happens is the o2 sensors give duff signals because of the DPF, in turn the MAF goes a bit haywire n attempts to default a working parameter until the signals go too much out of acceptable tolerance with the ecu. Then it kicks it into limp mode. I would strongly suggest 2 forced re-generation sessions. 1 at least . And if you havent changed ur oil or oil filter in the last 6 months then change them. These problems combined will ALWAYS point to your EGR being faulty in some way or other when in actual fact they are not faulty. These things barely ever go faulty. Hence the reason why they get changed and the problem is still present. If there is one thing I learnt about mercedes over the years its a code can be a false positive kicked up by something else. If you end up with a plume of black smoke and its constant. Including slight drops of wet oil on your tail pipe. Its most probably not your turbo so dont freak out. The build up causes the breather system to also block which can be quite frightening at first if u dont understand whats going on. Bits of wet oil and soot dumped into your cat aswell. Not good but not the end of the world and most of the time NOT requiring a new cat. Change your oil and filter and get a forced regeneration on your DPF. Im not entirely convinced with them DPF sensor numbers, as in was it the correct one that was fitted but Im going to check up on it because I made a list of DPF sensors with cross reference numbers. Can you double check your 1st dpf sensor number u listed. I dont think its right. So many people will say oh yeah they been updated at such n such month year blah blahhhh but erm its not the case. Ive found that some of the sensors on the vans should have been fitted to the saloons. Why ? no idea but they worked with better parameters, lasted longer and did not go intermittent.
DO A FORCED REGEN BEFORE THESE STEPS. IT WILL DO NOTHING BUT GOOD.
Step 1 check your oil level ( dont trust the oil level monitor too much, dump ur oil out see how much comes out if ur not sure )
Step 2 change your oil filter
step 3 change your oil
step 3 remove and clean your EGR valve ( it is a very easy job to do, dont attempt it with small pliers or anything. use a large flat end crow bar once u get the bolts off and if u wedge the flat end of the crow bar at the edge of it and some pulling n pushing forceful movements on it will loosen it enough to get it off. dont be afraid to give it some force. once it moves a little it will come off no bother) im getting fed up hearing people say they cant get it off its stuck. thats because their using the wrong tool and its too small.
step 4 DO ANOTHER FORCED REGEN
step 5 clear codes.
step 6 let car cool down
step 7 take it for a thrash
step 8 re-check for error codes. delete any
they will not come back after last step if everything is done properly
Thought it might be useful to post up here how I have hopefully got rid of the above fault codes both of which relate to the catalyst and/or exhaust temperature.
My car is a 2005 E320 CDi with the inline 6 engine - code OM648
The car repeatedly went into limp mode and showed the following codes
P0426
P2084
P1409
I changed the DPF Pressure differential sensor which is situated in the engine bay behind the gearbox.
The part number on my existing sensor was A0117 329 5603 but I believe that this was replaced by A642 905 01 00 - at least that is what MB parts told me. Cost about £60.
The new part seems to have done the business in respect of the first 2 codes but I am still getting the P1409 code which I think is related to the EGR but I'm not sure exactly what the fault is.
I did read a post (on here I think by a member called HITECH) who said that this P1409 code could be generated by the DPF sensor and who recommended putting heat sink past where the sensor is bolted to its mounting bracket.
I tried that today but it doesn't appeared to have worked.
So I seem to have solved part of the problem but not all and hopefully this post will help anyone who has only the first two codes.
