TheTwig
New Member
Hi, I'm new to the forum but I am hoping for a little help or direction. Apologies for the big read but wanted to give an overall account of events.
The EML came on whilst driving on the motorway but with no change to drive. Read codes using Autel OBDII scanner. At this stage there was 1 code present which was the P0101. I know this code is related to the MAF so began my investigation. No whistling sound and no obvious signs of split hose. Carried out some voltage checks on the MAF wiring and identified the supply and earth. This is a 4 pin connector so I back pinned the remaining 2 wires and hooked up multi meter to the pins assuming these are the signal wires. Started the engine and idle voltage settled around 0.85 volts. Slowly increased engine speed and voltage began to rise steadily as expected. Rather than keep increasing the voltage tops out at 1.1 volts. As the revs decrease the volt reading decrease gently and settle again. I figure the car is now in limp mode as I can't rev past 3000rpm.
Removed the MAF to give it a good clean but in all honesty it looks pretty spotless, but gave it a good spray of MAF cleaner anyway. Reassembled to car and cleared out the codes before starting but no difference. After a couple of drives the car (worth noting it's a manual) EML comes back on. I bit the bullet and ordered a new MAF from Mercedes.
While waiting and still not convinced it's the MAF, with the help of someone I managed to fined a small split in the underside of the intake charge hose so feel this could be the cause of the original MAF fault. Ordered the new hose and fitted thinking happy days. When I plugged in the scanner to clear out the codes to my dismay I now have 2 DTCs. The first being the P0101 for the MAF which I expected and the second is P2463 - Diesel particulate filter restriction - soot accumulation. My thoughts are that this soot has accumulated because regeneration has not been taking place whilst stuck in limp mode. Cleared out the trouble codes thinking I would just give car a nice long run keeping revs between 2-3000rpm to start regen process. However having replaced split hose all is the same. Still can't rev past 3000rpm and the same two troubles codes reappear. I haven't fitted new MAF yet (given the cost) as I thought split would be the cause of the MAF error.
I have read a couple of threads that suggest I may need a forced regen of the DPF using Mercedes star
I can't read the soot values with my scanner but I have had another scanner reading that says that at idle the exhaust back pressure is 0 so I wasn't thinking I need to rush out and get new DPF just yet.
Therefore my questions are:-
Do I really need a forced regen of the DPF?
Could the P0101 related to the DPFs soot accumulation?
Would a Faulty MAF stop engine revving or is this just caused by limp mode?
Any help would be greatly appreciated.
Thanks
The EML came on whilst driving on the motorway but with no change to drive. Read codes using Autel OBDII scanner. At this stage there was 1 code present which was the P0101. I know this code is related to the MAF so began my investigation. No whistling sound and no obvious signs of split hose. Carried out some voltage checks on the MAF wiring and identified the supply and earth. This is a 4 pin connector so I back pinned the remaining 2 wires and hooked up multi meter to the pins assuming these are the signal wires. Started the engine and idle voltage settled around 0.85 volts. Slowly increased engine speed and voltage began to rise steadily as expected. Rather than keep increasing the voltage tops out at 1.1 volts. As the revs decrease the volt reading decrease gently and settle again. I figure the car is now in limp mode as I can't rev past 3000rpm.
Removed the MAF to give it a good clean but in all honesty it looks pretty spotless, but gave it a good spray of MAF cleaner anyway. Reassembled to car and cleared out the codes before starting but no difference. After a couple of drives the car (worth noting it's a manual) EML comes back on. I bit the bullet and ordered a new MAF from Mercedes.
While waiting and still not convinced it's the MAF, with the help of someone I managed to fined a small split in the underside of the intake charge hose so feel this could be the cause of the original MAF fault. Ordered the new hose and fitted thinking happy days. When I plugged in the scanner to clear out the codes to my dismay I now have 2 DTCs. The first being the P0101 for the MAF which I expected and the second is P2463 - Diesel particulate filter restriction - soot accumulation. My thoughts are that this soot has accumulated because regeneration has not been taking place whilst stuck in limp mode. Cleared out the trouble codes thinking I would just give car a nice long run keeping revs between 2-3000rpm to start regen process. However having replaced split hose all is the same. Still can't rev past 3000rpm and the same two troubles codes reappear. I haven't fitted new MAF yet (given the cost) as I thought split would be the cause of the MAF error.
I have read a couple of threads that suggest I may need a forced regen of the DPF using Mercedes star
I can't read the soot values with my scanner but I have had another scanner reading that says that at idle the exhaust back pressure is 0 so I wasn't thinking I need to rush out and get new DPF just yet.Therefore my questions are:-
Do I really need a forced regen of the DPF?
Could the P0101 related to the DPFs soot accumulation?
Would a Faulty MAF stop engine revving or is this just caused by limp mode?
Any help would be greatly appreciated.
Thanks
