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+---- Thread: N47 DPF backpressure sensor problem (/showthread.php?tid=62285)
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N47 DPF backpressure sensor problem - Krysiaman - 21-03-2022
Hi!
I have a strange problem with E84 N47. Backpressure sensor shows 20mbar when engine is off, and 23-25mbar when idling. DPF was just cleaned in specialised workshop, backpressure sensors is brand new OEM (also tried Hella and other OEM but used).
Because of that DPF is regenrating too frequently or sometimes it will throw 480A and 481A code and won't renegenrate until I clear the codes but filter is not clogged.
Anyone had something similar?
RE: N47 DPF backpressure sensor problem - leo04 - 21-03-2022
Is dpf still ok? i suspect your DPF is clogged.
RE: N47 DPF backpressure sensor problem - Krysiaman - 21-03-2022
It's clean. I Can remove it and it still shows 20mbar when engine is off. Shouldn't it be 0?
RE: N47 DPF backpressure sensor problem - Node - 21-03-2022
Have you checked what pressure you read with pressure tube disconnected? If OK - then tube/DPF is clogged. If not - then something electrical.
RE: N47 DPF backpressure sensor problem - diagso - 21-03-2022
Do you have a tune on DDE ? For my adjusting EGR valve solved the issue. I assumed that DPF is not liking the tune.
I was having same issues. First DPF went for a wash, still simmiliar errors. Replacement of various backpressure sensors. Same story.
RE: N47 DPF backpressure sensor problem - Krysiaman - 21-03-2022
(21-03-2022, 21:02 PM)Node Wrote: Have you checked what pressure you read with pressure tube disconnected? If OK - then tube/DPF is clogged. If not - then something electrical.
I will check that tomorrow.
(21-03-2022, 21:49 PM)diagso Wrote: Do you have a tune on DDE ? For my adjusting EGR valve solved the issue. I assumed that DPF is not liking the tune.
I was having same issues. First DPF went for a wash, still simmiliar errors. Replacement of various backpressure sensors. Same story.
What do You mean by adjusting EGR?
Car is totally stock
RE: N47 DPF backpressure sensor problem - unicoil - 22-03-2022
If you disconnect hose from sensor is the reading still 20mbar? What is the I-level of the car?
RE: N47 DPF backpressure sensor problem - cursor - 22-03-2022
Vehicle management -> Troubleshooting -> Function Structure, next find "exhaust gas pressure sensor"
In ABL choos Functional check, and compare pressure to ambient pressure.
Many times i did have exhaust backpressure sensor that shows 1040 hpa, compared to atmospheric sensor showing about 1000 hpa. Permissible difference is 20 hpa.
RE: N47 DPF backpressure sensor problem - Krysiaman - 22-03-2022
(22-03-2022, 06:33 AM)cursor Wrote: Vehicle management -> Troubleshooting -> Function Structure, next find "exhaust gas pressure sensor"
In ABL choos Functional check, and compare pressure to ambient pressure.
Many times i did have exhaust backpressure sensor that shows 1040 hpa, compared to atmospheric sensor showing about 1000 hpa. Permissible difference is 20 hpa.
I tried now with another sensor. Now it shows -15mbar when engine is off or when hose is disconnected.
In ABL i have:
Atmospheric pressure: 1029 mbar
Charge pressure: 1059 mbar
Exhaust backpressure: 1014 mbar
Can it be charge pressure sensor?
RE: N47 DPF backpressure sensor problem - unicoil - 22-03-2022
When exhaust backpressure sensor shows negativ pressure then in my experience this is due to faulty backpressure sensor. It is very common to go bad like this on backpressure sensors, I have changed with that kind a fault tens of sensors, after that were pressure readings OK. I recomend to use only OE senors.
What is the value of the sensor with a new OE sensor and hose from the sensor disconnected?