Eurovan2 Forums - View Single Post - 2.2 hdi Blocked diesel filter message ECU faulty???

printertosh · 6th July 2009, 19:42

Thanks for your replies.
Had another look at the voltages today. With the engine off I've had a an improvement to 1.7v and now only getting a bleep everytime I pull away to say the filter is blocked but the yellow engine light has now gone out and NO limp mode! I'm convinced that this suggests that the Pressure differential sensor is faulty. I might have to replace it and see what happens. I'm sure that the ecu relies on the pressure differential sensor being connected and acting as a variable resistor to be able to bring the voltage down to 0.5v. If you disconnect the sensor and test the end of the wire coming from the ecu you get a constant 4.91v from the number 1 pin - pressure information (not 0v as some have suggested), Earth from 2 and constant 5v feed from 3. I'm guessing with the engine off and the pressure equal either side of the sensor the electrical resistance of the sensor is at it's greatest. Once the engine is running and the pressure either side is not even the electrical resistance of the sensor reduces, if the pressure difference gets too great the sensor eventually allows too much voltage through (more than 4.1v) and declares the particulate filter blocked.

Please let me know your thoughts on this and hopefully this information could prove useful to others. Thanks again. Paul

6th July 2009, 19:42	#4 (permalink)
printertosh Fledgling Join Date: 23 Dec 2008 Location: England Age: 38 Posts: 15 Thanks: 7 Thanked 2 Times in 2 Posts Car: Peugeot 807 Country of origin:	Thanks for your replies. Had another look at the voltages today. With the engine off I've had a an improvement to 1.7v and now only getting a bleep everytime I pull away to say the filter is blocked but the yellow engine light has now gone out and NO limp mode! I'm convinced that this suggests that the Pressure differential sensor is faulty. I might have to replace it and see what happens. I'm sure that the ecu relies on the pressure differential sensor being connected and acting as a variable resistor to be able to bring the voltage down to 0.5v. If you disconnect the sensor and test the end of the wire coming from the ecu you get a constant 4.91v from the number 1 pin - pressure information (not 0v as some have suggested), Earth from 2 and constant 5v feed from 3. I'm guessing with the engine off and the pressure equal either side of the sensor the electrical resistance of the sensor is at it's greatest. Once the engine is running and the pressure either side is not even the electrical resistance of the sensor reduces, if the pressure difference gets too great the sensor eventually allows too much voltage through (more than 4.1v) and declares the particulate filter blocked. Please let me know your thoughts on this and hopefully this information could prove useful to others. Thanks again. Paul
printertosh is offline