P0196 on BMW: Causes, Symptoms and Fix Cost

On most modern BMW engines there is no standalone oil temperature sender. The oil temperature comes from the combined oil condition sensor bolted into the bottom of the sump, the same unit that measures oil level for the condition based service system, and BMW uses that design across the modern petrol and diesel range including the current six-cylinder diesels, the N57 and B57. It does not project back indefinitely: early 2000s cars with the first M57, the E39, E46 and E53 era, use a simpler thermal oil level sensor together with a separate oil temperature sensor, so check what your engine actually has before ordering a part. On the engines that do carry the oil condition sensor it also reports an oil quality channel, but that is not something every diesel has. Two things follow. First, you cannot test it like an ordinary two-wire temperature sender: it is a small electronic module that reports to the engine ECU over BMW's single-wire BSD data line on a power, ground and data connection, so measuring resistance across the pins tells you nothing, and a BSD wiring fault can upset several components at once. Second, when it fails you usually lose the oil level reading as well, so check the level by hand until it is replaced. The connector sits directly under the engine and gets soaked in road spray and salt, and oil creeping down the harness from a leaking valve cover or oil filter housing gasket above is a well-known way to ruin it, so inspect the plug before buying anything. Genuine BMW sensors are expensive and OE-equivalent aftermarket versions cost less, and the car has to be lifted and the oil normally drained, so plan an oil and filter change at the same time. P0195 and P0196 very often turn up together on these engines and both come from the one sensor.

The 5 Series uses the same sump-mounted oil condition sensor as the rest of the modern BMW range, so oil temperature and oil level both come from one unit bolted into the bottom of the engine and reported digitally to the DME, with an oil quality channel as well on the engines that carry it. It is not a resistance sender, so a meter across the pins proves nothing: it sits on BMW's single-wire BSD bus alongside the intelligent battery sensor, the alternator and the glow plug module, which is why a BSD wiring fault can upset several of those units at once. Because the sensor sits at the lowest point of the engine, its connector takes the worst of the road spray and winter salt, and oil creeping down from a leaking valve cover or oil filter housing gasket above can bridge the pins, so inspect and dry the plug before buying a sensor. Replacement means lifting the car and draining the oil, so have an oil and filter change done at the same time. P0195 and P0196 together on this platform is normally one dropped sensor signal, not two faults.