DPF light on and off

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xdata
Posts: 3
Joined: Fri Apr 10, 2020 6:46 am

DPF light on and off

Post by xdata » Fri Apr 10, 2020 7:41 am

Hi all,

On my Passat B8 ( CRLB engine ) DPF light came on and stay for few minutes and goes off and after a couple off minutes came on again.
Also showing on Infotainment system warning for DPF filter.
As per attached picture light should be off because the Soot mass calc. is 9.36 gram.
As per red icons on DPF app looks like ECU regeneration was interrupted and and waiting for next trip to start regeneration again, also regeneration duration looks to long ( 92 min ).
My question is why DPF light is on if Soot mass is only 9.36 gram?
Thanks for help in advance.
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WhatsApp Image 2020-04-09 at 12.50.47.jpeg

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admin
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Joined: Sun Jun 02, 2019 10:58 pm

Re: DPF light on and off

Post by admin » Fri Apr 10, 2020 3:23 pm

Just a question: why the "Time since last regen" field is disabled?
If the grayed value inside it is coherent with the other values on screen, I think your engine performs the regeneration just because it has reached the limits of maximum time or mileage. This is a protection feature to avoid risk of fire in case of components failure.

The best is to check the ECU error log with a diagnostic software. At least an error should be present related to the warning lamp.

A frequent failure is the differential pressure sensor fail. Without this information, the ECU can't estimate the DPF soot filling and this should be the reason why you see a low soot mass value and the regen doesn't start regularly.

These are hypothesis, you should verify with a diagnostic tester or asking to a technician.

Let's know what you discover.

xdata
Posts: 3
Joined: Fri Apr 10, 2020 6:46 am

Re: DPF light on and off

Post by xdata » Fri Apr 10, 2020 6:43 pm

Hi,
Field " Time since last regen " was accidentally disabled.
First of all the car has been driven for a very short distances ( only few kilometers ) in last 40-50 days so looks like could not complete the regeneration process and because of that it's reached that " TIME LIMIT", like you mention. After the car being driven for 20-30 min. DPF light went off, also there is no errors in ECU, by VCDS. On attached picture is visible that regeneration is completed.
By the way, could you please tell me diference between Soot mass calculated and Soot mass measured?
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admin
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Re: DPF light on and off

Post by admin » Sat Apr 11, 2020 10:47 am

Ok so probably it was a temporary error. If you don't find any error using VCDS, it should be ok. The critical errors remain always registered, the others are removed by the ECU when the problem is solved.

Soot mass measured and calculated: this is a common question, the calculated value is the parameter used by the ECU (and by my app) to check regulate the regeneration process, the measured value use isn't clear to me because is sometimes goes below 0 that is impossible, and often it changes without linearity.
I added the measured value because some users asked for it, they said it becomes useful in case of failure of some sensor, in this case the calculated value isn't correct and the measured is the only way to understand the condition of the DPF. I didn't tested this condition because I never had failures with my DPF, but trusting on them (they was many different users), I added the parameter.

xdata
Posts: 3
Joined: Fri Apr 10, 2020 6:46 am

Re: DPF light on and off

Post by xdata » Sat Apr 11, 2020 6:16 pm

Thanks for explanation and thanks for really excellent and useful app.

Regards,

Neno

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