DPF sensor replacement?

yablonski

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Hey guys,

Apologies if a similar question has been posted regarding DPFs as I can see a lot of past threads.

I had my DPF force regen’d from my local indy last month, since then I’ve been driving the vehicle once/twice a week on the motorway at a consistent speed etc. Other than that the car is parked up for the remainder of the week currently, no short journeys.

Yesterday after coming off the motorway (45 minutes or so) it was trying to regen and I’m not sure if it should have been? I have driven it around 200-250 miles (again pretty much motorway miles) since the indy did the force regen.

I’m wondering if I have faulty sensors? For some context the Indy gave me a report, see attached.

Is it it worth getting the front and back sensors replaced?

thanks in advance!
 

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yablonski

yablonski

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Nope, no limp mode, drives fine, just changes gear at a higher RPM, 2-3k.

It just happens too frequently and since I just had it force regen'd a month ago and have only been doing motorway journeys I thought perhaps a sensor is faulty?
 

Tuercas viejas

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For info
The DPF has a sensor reading the the gas pressure fore and aft of the DPF.
Its measuring the actual back pressure within the component in HPa . Connected by two pipes and flexi hoses it sends out a signal to the ECM having an internal diaphragm style piezo sensor reading back pressure differences .
Remember DPF "diesel particulate FILTER " , so its actually measuring how much the filter is plugged up with soot and ash. (Because boiled down its just a filter and has a finite life just like any fuel or air filter.)

First tech inspection in the shop (& then on a road test) are the sensor pipes, (gas tight), plus the wiring harness and the connector for integrity . Then road test and obtain actual DPF pressures from live data on a scanner, because the codes are only an indication of a potential fauilt . Scan for actual recorded soot & ash content as a precentage.

EBP
Exhaust back presure sensor. Located aft of the turbo. The ECM needs to know how much the turbo back pressure is being developed. It will be influencd by DPF & Cat back pressure flow status & its not only has a direct infuence upon turbo performance but its sensor output live data info determines EGR operation, & front end blow pressure delivery. (amonst other things )
Notorius for water/ moisture ingress into the telescope plug it reads false info, or is often flat lined on a scanner.To read it remember with the engine in KOEO the atmosphere will fill all the exhaust & all the engine intake guts with atmospheric pressure . Being in the UK you will see something like 1000 to 1100. Me at 6500 ft will read about 700. baro pressure. Now go KOER and road test reading the actual back pressure.If its more than 2500, Its We have a problem Houston . :eek:

First your tech should have given you actual live data as a scanner print out and attach the same for shop records on the R/O & on your billing .
Second doing a static forced re-gen, or even an extended forced regen on a road test can have detrimental effect upon the DPF internal brick. With temps souring excess of 1000 c, it can fragment and go "kabboom" inside so beware .
So need figures , live data figures .
Tuercas Viejas
 

OneForTheRoad

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The dpf sensor and back pressure have nothing to do with revs and gear changes. If its not going limp then there's no issues with either component. For what they cost and if your concerned ,well change them . :)
 

Tuercas viejas

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The dpf sensor and back pressure have nothing to do with revs and gear changes. If its not going limp then there's no issues with either component. For what they cost and if your concerned ,well change them . :)
Sorry that's not striclkly true with a modern car and intercommunication between engine and transmission.
Besides just throwing parts at it is known as "shot gunning" in the trade & its rarely successfull but is also expensive.
The exhaust system being today an intergral part of the engine and not a tubular appendage with a chrome as in yesteryear, any perfomance issues should be treated by checking both engine & transmission performance figures observed in live data and not rely on just codes only.
Tuercas Viejas
Colorado State appointed emissions repair centre owner
 

OneForTheRoad

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Sorry that's not striclkly true with a modern car and intercommunication between engine and transmission.
Besides just throwing parts at it is known as "shot gunning" in the trade & its rarely successfull but is also expensive.
The exhaust system being today an intergral part of the engine and not a tubular appendage with a chrome as in yesteryear, any perfomance issues should be treated by checking both engine & transmission performance figures observed in live data and not rely on just codes only.
Tuercas Viejas
Colorado State appointed emissions repair centre owner
Obviously they play a part when there faulty . I myself have found this out . But only when in limp mode . The op says no limp mode detected and that the car is running fine. The op also seems to know when the car is doing a regen . Curious as to how .
 
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yablonski

yablonski

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E220
“The op also seems to know when the car is doing a regen . Curious as to how .”

Well I presume it’s when the engine note changes and it holds gears for longer which it doesn’t normally do, it tends to change at over 2,000RPM, it’s audible and noticeable.

Unless I’m mistaken! 😅
 

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