DPF power issue - limp mode

[400ixl]

It could be the soot content is just to high to do a regen, start with the cheapest option first, find your dpf sensor (probably on the rear of your airbox) and buy 1 can of dpf cleaner it comes with a line attached to go down the fat dpf pipe. follow the instructions on the can , its an aerosol and literally is a 5 minute job. take for a good run at 2-2.5 rpm . then get the light turned off mine went off on its own after a few more start ups.

It is the MAF/MAP sensor which is in the air system, not the DPF sensor which is in the exhaust.

Whoever switched off the light should also be able to readt the basic code. Assuming they used something like Torque on an Android phone and a bluetooth ODB reader. This can read codes as well, but not always to the deep level.

The EML will come on again when it is triggered. For example if it is the Exhaust temperature sensor then you can reset it and it will only come on again when the car does more than 1500RPM and 10mph. On tickover or stationary it wouldn't come back on.

Likewise, LIMP mode only activates after certain conditions are met. for example when a regen is required, but something is stopping it from being able to. As a regen would not be activated until up to a certain temperature, the LIMP mode won't kick in until then.

 

[umblecumbuz]

Assuming this IS a dpf related fault, and it does not seem that you have conclusively determined this yet because the car has not been scanned with dedicated MB equipment, then quite honestly you can either keep throwing time and parts at your car, or get it to an MB dealer/Star equipped Indie and have the diagnosis - and remedial work - done properly.

Shortcuts are often the long way round.

 

[Mr Filipov]

I don’t know how clear people need to be really on this one as has been pointed out a few times. Take it to a indie or main dealer (screw the £120 diagnostics) even though you know what it is, trust me it can save you a lot more if somethis else was to go as well in process like the DPF or the turbo, due to high back pressure (again, your call).
Someone needs to force a regen which once initiated can run with the car stationery anyway. All you are doing at the moment is building up more soot in there. The consitions are not being met in order for a regen to run actively and there is nothing you can do about it. All you are doing holding it at 3k rpms is building up even faster than normal driving.

 

[MBWill]

any decent diagnostics kit can enable a forced regen cycle

a car driven correctly will never play up

one abused round town and never exercised on the open road, just gets worse and worse, by the time most owners decide it needs the dealership the abuse is too much for the DPF to cope

once a week 20 mile run at 80 mph and 2500 rpm. if you spend time doing 2 mile runs to school and then commuting in traffic make it 3 times a week

I regularly drive this car, virtually almost every single day, and often for at least an hour a day if not more, on long drives, anywhere from say 10 miles to 120 miles, if the DPF isn't performing a regen when it needs to bearing in mind what i've just said then bugger me.

As mentioned in my previous post, i'll be taking it to a local indie (sod the dealers and their ripoff diagnostic prices!) to be looked it as soon as practicable given the public holidays.

I'll post back here once I know what the issue is.

 

[MBWill]

So a slight update for you, having spoken to a local indie dealer, they are not open until the new year, and it would have to be a "private job" otherwise it would cost a fortune at the garage's labour rates, the guy wants the vehicle "for a day" to look it over with a fine toothcomb.

Another local mechanic to me apparently hasn't got the STAR diagnostics kit to diagnose it.

In the meantime i've picked up an OBD scanner and had a goosey myself, it would appear to be an issue with an exhaust sensor, see below pics, and not the DPF clogging up.

I still plan to take it to an indie that won't charge an arm and a leg, in the new year, when they are open and will do private jobs so it doesn't cost me a fortune in labour cost.

 

[alex cnwell]

looks like a mb11 scanner ? they are good arnt they , excuse me but isn't this just the dpf sensor? on the rear of the airbox , its like a 2 min job .

 

[400ixl]

Good news is the DPF level which gives you some leeway in getting it fixed. There are two sensors which need to both the within a set range individually and a set range of each other as well. So it could be more than one of the sensors.

From memory, the sensors are around the £80-100 area each. Takes about 15 minutes to change one on a ramp, so should all be done within an hours labour.

 

[400ixl]

looks like a mb11 scanner ? they are good arnt they , excuse me but isn't this just the dpf sensor? on the rear of the airbox , its like a 2 min job .

Sensors for the DPF are in the exhaust not in the air intake system. The MAF sensor is in the air system, along with the EGR valve.

 

[MBWill]

looks like a mb11 scanner ? they are good arnt they , excuse me but isn't this just the dpf sensor? on the rear of the airbox , its like a 2 min job .

It's actually a Launch Creader CRP 123, I did weigh up that versus the MB II however the MB II only works with MB vehicles, and my dad's Ford has a fault so figured would be good to kill two birds with one stone and get one that works with multiple brands.

So at this stage it's still inconclusive, how would one go about pinpointing to see exactly which sensor it is? I don't intend on replacing all the sensors mentioned given the cost if certain sensors are working perfectly fine.

Would a STAR machine tell me exactly which sensor it is?

I'd assumed the exhaust back pressure sensor was just another name for DPF sensor, which to my understanding is the sensor that has the two pipe connections going to it, and it costs around £60 new.

From what I've seen online it's also fitted in the engine compartment somewhere.

Reading other posts with the same issue seems to suggest it's the B60 sensor which is located in the engine bay, and is between £40 and £60 for a replacement.

 

[alex cnwell]

on my w203 c220 the DPF sensor has 2 pipes which connect directly to the exhaust to monitor back pressure, this on my model is located on the rear of the airbox, its merely a back pressure sensor which i presume measure the load from the dpf, thats the one i would change.