Quote:
Originally Posted by delcomb
Grant, this sounds like the tank level sensor is the discrete type. I did some work on testing the pump systems for one of the manufacturers. There were some with ultrasonic level sensors that gave a continuous output. Others had a magnetic float and several reed switches to indicate only certain level points (empty, almost-empty, 1/2 full and full). Looks like Volvo uses the float/reed switch type. So the tank had to be filled enough to trigger the right switch to reset the fault.
Doug
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Hi Doug,
I think you are right. The digital display for the Ad-blue tank seems to have 4 sectors. After tipping in 3.5 ltrs to a not completely empty tank (and with no idea of its total capacity) it was showing half full and the warning message was gone. I did wonder if the slight slope on which the car was parked might be enough to confuse the sensor - but heck, this is a rugged 4x4 so if parking with 2 wheels on a low kerb was enough to cause a problem with an apparently half full tank what would some real off-roading do?
We did actually try rocking the car side to side to see if it might just trip something. Or might clear an air lock (there was a warning about potential air locks in the documentation). The rocking worked in so far as we could get the car to move and jiggle fluids around. But no luck with it getting the engine started by allowing the reset - unless the very specific steps of the systems reset would mean the rocking was never going to work with the check sequence.
I even considered trying to tow it a couple of vehicle lengths so it was off the kerb but decided that my Saab and tow rope might not be up to the job for an XC90 with parking brake applied!