4.4 Other sensors 4 WIRING
Pin Function OEM wire color Connection
B MAF output signal White MS3Pro analog input
D Ground Black MS3Pro sensor return
E Switched 12 volts Black / white 12 volt fused supply from main relay
4.4.5 Oxygen sensors
The MS3Pro can accept input from a narrow band O
2
sensor directly; simply wire the narrow band sensor signal
to the O2 input wire on the MS3Pro. Narrow band O
2
sensors may have from one to four wires. Here is what to do
with the wires depending on the type.
• Single wire: The wire is the sensor signal and it grounds through the body.
• Two wires: One wire is the signal and the other connects to the sensor ground.
• Three wires: This is a heated sensor. In addition to the signal wire, there is a heater wire that connects to
a switched 12 volt source, and a ground wire which should be connected to the engine block as the heater
draws more current than we recommend applying to the sensor ground wire.
• Four wires: These have a signal wire and a sensor ground wire which connects to the MS3Pro sensor ground
wire. The two heater wires are normally the same color. One connects to a switched 12 volt source and the
other can be grounded to the engine block or chassis.
As a general rule, if the sensor has two wires that are the same color, these two wires are for the heater, and may
be hooked up either way. Bosch’s wire coloring system is the most common, and looks like this:
Function Color
Signal Black
Sensor ground Gray
Heater White
Heater White
However, there are several other color schemes out there; if you run into a different set of colors, consult a
factory wiring diagram for your vehicle.
The MS3Pro can also work with most aftermarket wideband oxygen sensor controllers. You will need to install
the controller according to the directions that came with it, and connect the controller’s analog output wire to the
MS3Pro’s oxygen sensor input wire. If the wideband controller has a ground specifically for its analog output, it
connects to the MS3Pro sensor ground wire. Do not connect any wires labeled “serial output”, “digital output” or
similar to the MS3Pro, or connect any other sort of wideband ground to the MS3Pro. Here is a list of what wire to
use with common wideband controllers.
AMP EFI MS3ProUltimate manual version 1.203, firmware 1.5.0, 5/23/2017 Page 45
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