What uses 3 pin oil pressure sender?

Can you order the GM one from your local Vauxhall dealer?

Rover sd1V8 had a three pin oil sender
At least mine did

Thanks for the comments, I will probably end up making a 5v stabilised supply as part of the solution. There is a 5v supply output from the arduino onboard regulator, but not convinced it would run multiple sensors happily.

I have found one sensor but its a chinese special hence looking for a more oem solution which is also likely to be chinese made but hopefully reliable.

Not the cheapest solution, but I tend to use the Tracopower TSR 1-2450 in any project that needs a stable 5v rail now. (or the 1-2433 for 3.3v rails). Wide input voltage range, very stable output, overcurrent protected, run cool and no need for any supporting components.

I think I've tried the cheap chinese sensor you're on about - the stainless steel bodies ones that are all over eBay? I didn't test it before putting it in the car, the reading (via arduino and OLED dispaly) jumped around all over the place. Put a scope on the output and saw this at idle:




That's showing lots of digital jumps between 0psi and 100psi. Excellent.

I have bought a 300PSI one to test and see if I have better luck, but so far I can't recommend the cheap ones!

You may find that it is the Traco DC - DC convertor that is causing these spikes. These are digital switching devices that use a high frequency oscillator to 'chop' the voltage. This can cause high frequency interference on the output which can react with certain types of load and induce noise spikes. Unless some pretty serious filtering is employed on the output they are not best suited to instrumentation supplies. I worked on engine test beds and was a specialist in instrumentation for some 35 years before retiring and from experience would not use chopper regulators because of the problems they can cause. A simple analogue regulator is not as efficient but is far better for instrumentation. Something like this: cpc.farnell.com/stmicroelectronics/l4940v5/ic-v-reg-ldo-5-0v-4940-to-220/dp/SC10587 with a capacitor across its output would do just fine.