1993 GMC C1500, engine is miles from stock as I have installed a BluePrint Engines crate motor that makes about 405 hp with a modified TBI fuel injection setup and headers. I have a tune which is working well but it's a little rough until the one-wire 02 sensor is warmed up on cold mornings. It's perfect from the start during the warmer months. I still slowly play with the tune but in the interest of continuous improvement I'm adding a heated O2 sensor.

So my question, I need to use a 12 positive source that comes on with with the key switch to power the heating feature. I'm trying to figure out if anyone knows how many amps a heated O2 sensor may draw. I was hoping to tap the circuit block on the firewall that powers the fuel pump but I don't want to overload the circuit killing the "critical" fuel pump.

Does anyone have experience tapping into positive keyed sources for this application.

Thanks