Technical DPF or Sensor issue?

[deejays]

Sounds good. Do you have to have cables, or can you connect via a wireless OBDII Code reader View attachment 476090
like I can with google free car scanner app

​

Either. But to access all modules you will need an cable adapter as per the attached from https://www.multiecuscan.net/SupportedVehiclesList.aspx
I use a Vgate vLinker MS Bluetooth which enable access to all modules without any extra interfacing cables. I suggest you have a look at https://www.multiecuscan.net/

 

[Killykix]

Hello, Quick update on my initial post (the conversation kinda drifted away ). We’ve replaced the DPF sensors with new ones (Bosch), and made our 3rd forced regeneration with a full tank of AD blue. All error codes went away, until we drove for 10min and warning light came back, without limb mode.
We’re running out of options. The only things left to do for us:
1. Disable entirely the AD Blue system
2. replace the AD blue sensors
3. Recalibrate the DPF sensor with disconnected pipes for the car to calculate 0 pressure in the open air
4. Remove entirely the DPF (what the garages here in Bulgaria want to do, but we don’t!)

If anybody has another idea, I’m more than open to hear about it, Thanks!

 

[jackwhoo]

Which warning light? What fault codes?

 

[deejays]

There is a history of the 2.3L AdBlue engine with regard to failing NOX sensors and soot sensors. A number had been replaced under warranty. One of the sensors in question is mounted under the bonnet near the top of the firewall - where the vacuum reservoir was mounted on the pre-AdBlue engine. The other sensor is very much downstream in the exhaust system and is mounted underneath towards the rear of the vehicle. If you have your vehicle at a FIAT PRO workshop then they should be able to diagnose the issue correctly for you and perhaps save you some money by not firing the parts canon.

 

[Killykix]

Which warning light? What fault codes?

Yellow engine light, not blinking associated with the message “Check engine”

Most recent error codes:

P1206-22; High flow resistance in Diesel Particulate Trap – Signal amplitude > maximum
P20EE-21; Urea NOx catalyst efficiency below threshold – Signal amplitude < minimum
P24A4-68; Soot Load too high and Mileage with Diesel Particulate Filter Lamp ON – Event info

 

[Killykix]

We read the new error codes at a garage, which gave us the following codes:

P220F-09 – NOx Sensor 2 performance
P06EB-92 – SCR efficiency below threshold

 

[jackwhoo]

Appears regen of dpf worked.

You have fault codes come back for nox reduction system = scr ,addblue , sensors

It could be faulty nox sensor or its wiring.
Or it could be something else to do with addblue system

Nox sensor 2 implies more than 1 nox sensor and code is for downstream sensor ie further away from engine than nox sensor 1. Together with the scr efficency code I wonder if nox sensor 2 monitors the scr performance.

Regardsless of the above nox does not cause soot and so wont block your dpf.

 

[Killykix]

Appears regen of dpf worked.

You have fault codes come back for nox reduction system = scr ,addblue , sensors

It could be faulty nox sensor or its wiring.
Or it could be something else to do with addblue system

Nox sensor 2 implies more than 1 nox sensor and code is for downstream sensor ie further away from engine than nox sensor 1. Together with the scr efficency code I wonder if nox sensor 2 monitors the scr performance.

Regardsless of the above nox does not cause soot and so wont block your dpf.

Indeed everything points to the NOx sensor 2, but a mechanic here told us that replacing it might not solve the problem. We don’t mind about the warning light on the dashboard if it’s just a faulty sensor, what we’re worried about is that limb mode will come back again. We’re considering disabling the entire SCR system as we don’t know what else to do

 

[deejays]

@Grayducato Can you perhaps advise considering what seems to be a similar issue you had some time back?

 

[jackwhoo]

Indeed everything points to the NOx sensor 2, but a mechanic here told us that replacing it might not solve the problem. We don’t mind about the warning light on the dashboard if it’s just a faulty sensor, what we’re worried about is that limb mode will come back again. We’re considering disabling the entire SCR system as we don’t know what else to do

I dont know if nox codes will cause limp mode. You could buy a cheap code reader to use yourself and if nox codes cause limp mode delete codes yourself.
Yes sensor may not be faulty , the code could be caused by add blue pump or block add blue injector or something else.
But if you want it fixed you have to start somewhere, i understand that there have been problems with nox sensor reliability.
If nox sensor not expensive I would suggest that as step forward.

If you are in a country with approved fiat proffessional mechanics it may be worth the extra expense of going to them.

 

[Killykix]

Hello, after disabling the ADBlue system and being able to drive for a few weeks, engine light is back on with the error code: P2002. It seems to indicate an issue with the DPF, but as you can on the picture attached, the pressure is actually low. How can a clogged DPF allows low pressure? We’re very worried of disabling or replacing the DPF, and that the problem would anyway come back

 

[jackwhoo]

Check pipes to pressure sensor.
Have You replaced sensor with known good brand?
Is there soot in exhaust pipe?

 

[Killykix]

Check pipes to pressure sensor.
Have You replaced sensor with known good brand?
Is there soot in exhaust pipe?

Sensor brand is Bosch. Pipes were quickly checked by a former mechanic, no condensation nor fissures found. We haven’t checked thoroughly, nor if there was soot. We assumed that if the mechanic would have found something in the pipe, he would have said something

 

[jackwhoo]

If there is soot in exhaust tail pipe the dpf may be cracked or damaged in another way allowing easy flow through dpf causing too low pressure reading, i do not know the parameters meaning too low pressure or even if it is too low.

 

[Killykix]

Thank you for your response. Is there any way to confirm visually if DPF is cracked? We’re very worried to replace it, but still having the problem coming back (considering the high price of a new DPF)

 

[jackwhoo]

Soot in tail pipe

 

[jackwhoo]

Would be good idea to get fault code read with code reader that reads 6 digits after the P as it gives more information

 

[lycopersicum]

I'm not sure that the P2002 is necessarily caused by the DPF being blocked or cracked. By the sound of it, it's about a successful regen being overdue, for reasons that may include DPF damage, but also other causes preventing regen.

Checking for a cracked DPF:

Wipe the tailpipe. If there's soot, the DPF has been cracked at some point in the past. If the history of the vehicle is unclear, you could wipe the tailpipe clean and check if the soot comes back after a few hundred kilometers.

A grossly cracked DPF will also show as abnormally low differential pressure under load, but I don't think a moderately cracked DPF can be easily distinguished based on pressure alone. At least I would have no idea where to set the threshold.

Checking for blockage:

Monitor the differential pressure at highway speeds. It should increase markedly over idle pressure but not exceed 100 to 150 mbar.

Again, blockage is not necessarily damage as it can also result from the regen not running on schedule. But if the regen does start and then fails with an error about the DPF, or fails to reduce the pressure to healthy values, and especially if the problem recurs shortly after a forced regen, that points to the DPF needing replacement. Note that the ECU will probably not attempt a regen while there are active error codes.

 

[Killykix]

Thanks, everyone. Very helpful. We have an appointment with a local garage here in Greece. They keep pushing us to remove physically and electronically the DPF, which we want to avoid at all costs.

Here is what we want to ask them. Let me know if I’m missing anything. I’m unfortunately afraid they won’t be able to do the following…

Current situation
• Vehicle is in limp mode
• Active fault code: P2002 – DPF efficiency below threshold
• Calculated DPF soot load: 134%
• Differential pressure is low (~21 mbar), which suggests the DPF is not physically blocked
• SCR / AdBlue system has been electronically disabled
• NOx sensor physically disconnected
• Forced regenerations have already been attempted and were not durable

There is a clear contradiction between:
• Low differential pressure (indicating low physical restriction)
• Very high calculated soot load (134%)

Need to verify the following ECU parameters:
1. DPF regeneration allowed status (YES / NO)
2. Active regeneration status.
3. Distance since last successful regeneration
4. Failed regeneration counter
5. Post-injection enable status
6. Exhaust gas temperatures before and after DPF
7. Any remaining regeneration inhibition flags, related to previous error codes

Required ECU resets (not just clearing fault codes), a full reset of DPF-related adaptations is required:
• DPF soot load model
• Distance counters since last regeneration
• Failed regeneration history
• DPF efficiency evaluation
• Regeneration inhibition logic
• SCR / NOx interaction flags (even though SCR is disabled)

 

[Killykix]

I'm not sure that the P2002 is necessarily caused by the DPF being blocked or cracked. By the sound of it, it's about a successful regen being overdue, for reasons that may include DPF damage, but also other causes preventing regen.

Checking for a cracked DPF:

Wipe the tailpipe. If there's soot, the DPF has been cracked at some point in the past. If the history of the vehicle is unclear, you could wipe the tailpipe clean and check if the soot comes back after a few hundred kilometers.

A grossly cracked DPF will also show as abnormally low differential pressure under load, but I don't think a moderately cracked DPF can be easily distinguished based on pressure alone. At least I would have no idea where to set the threshold.

Checking for blockage:

Monitor the differential pressure at highway speeds. It should increase markedly over idle pressure but not exceed 100 to 150 mbar.

Again, blockage is not necessarily damage as it can also result from the regen not running on schedule. But if the regen does start and then fails with an error about the DPF, or fails to reduce the pressure to healthy values, and especially if the problem recurs shortly after a forced regen, that points to the DPF needing replacement. Note that the ECU will probably not attempt a regen while there are active error codes.

The car immediately went into limb mode when engine light came on, which means that we can’t go to highway speeds unfortunately