I have located the mode 22 oil temperature pid (4402) and oil pressure pid (586f)

I can read the live data with an Ancel BM500 obd tool – they are available under the ‘motor operating values’ livedata menu.

I have the oil temperature reading close to expectations with

(B-64)*.77 Without the multiplier, the temperature values are too high.

For the oil pressure pid, bytes A and B seem to apply, with A’s first 4 bits being used. (the sensor is absolute pressure type – the BM500 shows 1058 with the engine stopped. (varies with atmospheric pressure)

With the engine stopped A is 9dec representing atmospheric pressure of 1058 hpa and increases with revs to 13-14, representing, I assume, a pressure range of 14-9 = 5000hpa (5bar).

However byte B is all over the place, almost randomly varying from 0 to 255. Maybe it’s nothing to do with the oil pressure
so I am in need of suggestions please?