Hi, we have an oil sensor problem, it reads the oil level as too high at 5.7 litres. This was diagnosed yesterday by a mobile diagnostic tech.The car was serviced last week by volvo, and had 5.2 litres installed. I can change the sensor fairly easily, but will it need the tech guy to come again to set it up?
BikerAndy
Which model and what engine? On VEA engines the sump sensor measures in millimetres. Changing it might affect the DIM oil level indication if the new sensor reads differently, but if you know that the oil quantity in the sump is correct, you can just ignore it until the car has travelled sufficient distance to recalibrate itself.
If it is a VEA engine though, I'd want to know how a mobile diagnostic is reading oil volume. The level is reported in millimetres. What that equates to in volume depends on the engine, as I believe there is some difference between diesel and petrol engines, and also between early and later petrol engines which have a redesigned sump. Diagnostic tools that I'm familiar with simply report the level in millimetres, there is no conversion to volume.
It appears from discussions I have seen elsewhere that some aftermarket diagnostic tools don't seem to report the level correctly either, as some owners reported obtaining different readings between tools on the same car.
So I would ask how the tech has confirmed that the sensor is faulty. Is he a Volvo tech sent out by the dealer? Did the dealer calibrate the oil level reading after changing the oil? The dealer calibration inserts a false good reading into the system to avoid low oil level or engine service required messages which can otherwise happen before the car has had chance to recalibrate itself. It wouldn't be the first time it has been forgotten, judging by other posts here and elsewhere. As you had recently had the oil changed that may be more likely to be what has happened?
If it is a VEA engine though, I'd want to know how a mobile diagnostic is reading oil volume. The level is reported in millimetres. What that equates to in volume depends on the engine, as I believe there is some difference between diesel and petrol engines, and also between early and later petrol engines which have a redesigned sump. Diagnostic tools that I'm familiar with simply report the level in millimetres, there is no conversion to volume.
It appears from discussions I have seen elsewhere that some aftermarket diagnostic tools don't seem to report the level correctly either, as some owners reported obtaining different readings between tools on the same car.
So I would ask how the tech has confirmed that the sensor is faulty. Is he a Volvo tech sent out by the dealer? Did the dealer calibrate the oil level reading after changing the oil? The dealer calibration inserts a false good reading into the system to avoid low oil level or engine service required messages which can otherwise happen before the car has had chance to recalibrate itself. It wouldn't be the first time it has been forgotten, judging by other posts here and elsewhere. As you had recently had the oil changed that may be more likely to be what has happened?
OK. You have a 4-cylinder VEA diesel engine. The maximum oil capacity for all of those engines for your model year is 5.2 litres, but they should not be filled to capacity. I still wonder if the independent mechanic understands how the oil level indication on these engines works. The sump sensor reports the oil level in millimetres (actually 100ths of a mm) in real time to the ECM, but the information which is then sent to the DIM (instrument cluster) is averaged over each journey, and the system requests oil or reports an overfill if it detects a deviation in the averaged level over consecutive drive cycles. So if the level before and after an oil change differs, the car will report an issue. Similarly if the ignition is turned on during the oil change, which it often is at a Volvo dealer as they may have the car connected to VIDA diagnostics throughout, the system will register the drained (empty) sump and fill as a deviation. So Volvo have a tool which programs a false good reading into the car, which persists long enough to give the car time over consecutive journeys to recalibrate its own reading.
It's best to start with a new known baseline. If you don't want to go back to Volvo (and nor would I if they insist on charging you a diagnostic fee every time) I would start by completely draining the oil. Then refill with a maximum of 5 litres. If you aren't changing the filter, and if it's just been changed there is no reason to, then only add 4.6 litres as there will already be 0.4 litres in the filter. The "normal" oil capacity for the car is between 4.4 and 5.2 litres (if it had a physical dipstick that would be the low and maximum oil level marks). There is no reason to aim for maximum capacity. The minimum and maximum levels are chosen so that the engine will operate safely and satisfactorily anywhere between those two levels, and I always prefer the oil level to sit between half and three-quarters between min and max, particularly on a modern diesel.
So after draining and refilling to 5 litres, you now have a known normal oil capacity. But you cannot carry out the Volvo calibration without the special tool. Don't worry. Just drive the car as normal and ignore any message asking you to add oil or telling you that the engine is overfull. The car should recalibrate itself after a journey of at least 20 miles and being parked on level ground before and after, although it could take a couple more journeys, and it may take several days if you are doing shorter daily commutes. But the warning messages should eventually go away. It's worth keeping an eye on the engine bay and underneath where you park the car initially, just in case of any real oil leaks, but if you haven't had any leaking or loss of oil beforehand there's no real reason to assume it will suddenly happen after an oil changed.
For added peace of mind, you can read the oil level in mm directly from the ECM with an android phone app called Car Scanner Pro, and the Volvo VEA engine profile add-on. You just need a cheap bluetooth OBD dongle to connect to the OBD port on the car. If you take a reading with a known good oil level in the car, you can check it regularly and will know if it drops.
Unfortunately this is what car manufacturers call progress
It's best to start with a new known baseline. If you don't want to go back to Volvo (and nor would I if they insist on charging you a diagnostic fee every time) I would start by completely draining the oil. Then refill with a maximum of 5 litres. If you aren't changing the filter, and if it's just been changed there is no reason to, then only add 4.6 litres as there will already be 0.4 litres in the filter. The "normal" oil capacity for the car is between 4.4 and 5.2 litres (if it had a physical dipstick that would be the low and maximum oil level marks). There is no reason to aim for maximum capacity. The minimum and maximum levels are chosen so that the engine will operate safely and satisfactorily anywhere between those two levels, and I always prefer the oil level to sit between half and three-quarters between min and max, particularly on a modern diesel.
So after draining and refilling to 5 litres, you now have a known normal oil capacity. But you cannot carry out the Volvo calibration without the special tool. Don't worry. Just drive the car as normal and ignore any message asking you to add oil or telling you that the engine is overfull. The car should recalibrate itself after a journey of at least 20 miles and being parked on level ground before and after, although it could take a couple more journeys, and it may take several days if you are doing shorter daily commutes. But the warning messages should eventually go away. It's worth keeping an eye on the engine bay and underneath where you park the car initially, just in case of any real oil leaks, but if you haven't had any leaking or loss of oil beforehand there's no real reason to assume it will suddenly happen after an oil changed.
For added peace of mind, you can read the oil level in mm directly from the ECM with an android phone app called Car Scanner Pro, and the Volvo VEA engine profile add-on. You just need a cheap bluetooth OBD dongle to connect to the OBD port on the car. If you take a reading with a known good oil level in the car, you can check it regularly and will know if it drops.
Unfortunately this is what car manufacturers call progress
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