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OX339/2D oil pressure problems after replacing filter?

MAHLE oil filter insert OX339/2D: oil pressure problems after replacing filter Click here to download the full report.


After replacing filter reference OX339/2D, it is possible that the oil pressure indicator lights up despite an oil pressure check not showing any significant problems. Often the oil filter is then suspected as the cause of the problem. Due to an increase in enquiries from garages and distributors about this phenomenon, the specialists at MAHLE have carried out various tests and identified the source of the fault.




The majority of oil filter housings used in original equipment and in the aftermarket have an integrated,

spring-loaded oil return valve. Unscrewing the filter insert releases the valve allowing the oil in the housing to flow into the oil sump. This ensures that the complete volume of oil can be drained during the oil change.


The purpose of the valve is to open the oil return channel when the filter is removed, and to close this

channel when the filter is fitted. However, experience shows that the sealing ring in the valve can become brittle—with the result that the valve jams and is unable to properly seal the oil pressure channel or the oil return channel, thereby preventing the build-up of adequate oil pressure.


The risk: because oil pressure is usually measured on the section between the oil pump and the oil filter housing, where no significant deviation can be identified due to the design, the fault is usually not noticed at this measuring point.




In order to prevent serious engine damage caused by insufficient oil pressure, MAHLE recommends to

check the valve’s freedom of movement before each oil filter change—the simplest way is to do so by hand, by directly actuating the valve or by briefly pressing the oil filter insert to be fitted into the housing. If the valve jams, or does not move freely to the upper stop, the oil filter housing should be replaced. The housing should also be replaced when the oil pressure indicator lights up after an oil change and there is no other plausible reason for it to be activated. Unfortunately, it is not possible to simply replace the valve because it is a press fit in the housing.