dgmark

I am having a problem with an Aim 0 to 150 PSI oil pressure sensor reading -18 PSI when the engine is off. It is an MXL2 dash, is there a calibration setting for the sensor or is the sensor bad.

ProCoach

No, and no. The "rest" voltage in mV can vary slightly. If you want to send it back to KA sensors in Massachusetts to be checked against calibration for positive pressure readings, you can, but that would not be a concern to me.

gobuffs

so is it off 18psi? So if the sensor would read 20 is it really 38 or is it 20?

ProCoach

Not necessarily and not likely. While the pressures read aren't absolute (taking into account altitude and barometric pressure changes), the rest pressure corresponds to a particular voltage output. If it's .479 V instead of .500 V at rest, it would read negative, and that is and has been my experience. As you supply pressure to the sensor, it's typically calibrated at points throughout its range, so 4.5 V would correspond to 150 psi present at the fitting.

So an error on the low side reading, IF it reads negative pressure at .500 V (500 mV) or low pressure (<150 psi at 4.5 V (4500 MTV) would be the only indication of a problem.

IF YOU HAVE DOUBT, send the sensor to KA and have them test it. Simple. Most of the failures I've seen are gross and pretty clear.

Matt Romanowski

KA is out of Danbury, CT, not Massachusetts, but I would not recommend going straight to them. If you bought it from an AiM dealer, then go through the dealer or AiM.

As Peter said, most of the time when a sensor fails it's pretty obvious. Check the millivolt reading in the live view screen and see if it's reading less than 500 mV. If it is <500 mV, then I wouldn't worry.

Also, what does the battery voltage show when the sensor is reading <0 psi?

jwasilko

I've had a couple of sensors in my car and friend's car do that. I talked to a couple of people at AiM and they're aware of it. Apparently their current sensor manufacturer (KA) doens't have a very good warranty.

I was told to create a new custom sensor with 0 being whatever mV the sensor was actually putting out with the car off (in the case of an oil pressure sensor).

dgmark

Thanks, I will check the resting voltage, My gut tells me that the sensor is also reading low throughout the range but I will check it against a mechanical gauge.

Chris P Lewis

That sucks..... sorry I had to.