ODB2 Power when car is off
 

I have a question....is the ODB2 port supposed to have power when the car is turned off and the key is out?


- I was getting increased discharge error in my E60, which I traced to my P3 gauge. Even thought the gauge turns off, it must draw some power. since I get the error when the gauge is connected but not when it is disconnected from the ODB2 port. It is still installed but disconnected--car gives no errors.


However


- I just got a Cobb and noticed it booted right up when I plugged it into the ODB2 port, even when I had the key out of the car.


Is that normal? should the ODB2 not draw power when the car is off?
also does anyone else have problems with their P3 gauge?


thanks

i noticed the same thing too when I use my BT OBD reader. Plugged it in while the car was off and no keys, and saw the LED's on the reader started blinking. I didn't bother looking any further since I don't keep it plugged in.

I once left my Bluetooth obd2 dongle plugged in overnight and it drained my battery so Yes there is always power on it I would think.

so then it seems my P3 gauge has an issue....

Please enlighten me what is a P3 gauge?

Google my friend google.....


BMW E60 - P3 Vent Gauge - P3 Cars


P3 Digital gauges provide the highest level of OEM integration and color match offering more features than any other gauges in their segment. Starting at a price competitive to single feature old-school needle gauges, they offer unmatched feature to price ratio.

All gauge models include an on-the-fly configuration menu for setting units (BAR/PSI for boost, and C/F MPH/KPH for multi-gauge values), as well as feature options, and ambient calibration. See www.p3cars.com/install for more details.




it worked awesome for over a year then now gives me a high discharge error overnight. It gave me a temp guage along with a lot of other things...

Thx, quite pricey as you can get similar data from many smartphone apps for a lot less $$.

True it is expensive, but it looks factory. I can scroll a lot of stuff through the display without needing to mess with my phone.


I found how to use my P3 gauge. I cut ODB2 wire 16 that leads to the P3 gauge and wired that wire to switched power. Thus the gauge no longer has access to the ODB2 constant power wire that leads to the battery and therefore cannot drain the battery.

You are likely only getting this error now because your battery is slowly dying. I believe once the computer (one of many) senses the battery is below a certain percentage of its life, it will give you the discharge error if there are slow drains present (i.e. your P3 or anything else plugged into your OBD port).

I thought about that and alternator charging well and my battery is about 1.5 years old. AGM BMW OEM and properly registered at time of installation. Good point though-- need to watch that closely.