How To Install a AEM Uego

How To Install a AEM Uego


AEM Wideband gauges have come a long way since being one of the first affordable aftermarket units available, but it’s still one of the strongest aftermarket mods you can install on your forced induction vehicle. With unsurpassed accuracy, speed and control, this wideband controller features a easy to read LED display with full-sweep LED lights to show you where your car sits on the stoich scale.



Couple this with the ability to output a 0-5v analog reading for use with data loggers and standalone PCM’s, and it’s easy to see why this 30-4100 is still a winner so many years later.

Today we’ll be showing you How To Install a AEM Uego in a 2008 Honda Fit, this vehicle has a few bolt on modifications and is meant to compete in the Honda Stock Class.



The part number we’ll be installing is a 30-4100, which is their baseline UEGO gauge entry that comes complete with all the hardware needed for the install.

First we must locate a spot on the vehicle that’s closest to the exhaust to provide for accurate .01 changes in the air/fuel reading, but far enough that it won’t kill our Bosch 4.2LSU sensor, which is what AEM uses in their widebands.

We’ll be drilling a hole and welding the supplied 02 bung in place to screw our air/fuel sensor in place, with the midpipe removed we mark down where we want the sensor installed and drill ourselves the appropriate sized hole.



Make sure to tack the bung in place first, and try a test fitment as the center tunnel to the Honda Fit is not always accommodating.  Make sure you are not running into or getting too close to the bevy of clips and wires that run behind your Fit motor.

Now that you are sure the UEGO sensor will not hit, melt or vibrate against anything, finish up the welding on the bung.

Now with the bung welded in and installed we can move onto the electrical wiring portion of our How To Install a AEM Uego guide.

Go inside the cabin and take apart your Honda Fit steering column cover, which is held together by 3 screws.



Now with the cover off, trace back the wires that lead to your ignition switch where we’ll be tapping both the orange and white wires for switched power. Undo your negative terminal on your battery in case you fry or damage anything while soldering.

Unplug your ignition switch ( brown harness ) and locate the white wire with a red stripe. This is the switched power to your car, tee the red power wire of the AEM UEGO to this wire in question. Then tap the black wire onto any chassis ground and secure it using a bolt or electrical ground strap loop.

This is a good time to check the gauge and make sure it lights up and looks good. You are nearing the end of our How To Install a AEM UEGO gauge, the next step is to run the loom.


Now might be a good idea to mount your gauge, but on the Honda Fit the available space to mount your gauge can be difficult given the design of the A pillar and lack of dashboard space.

After your gauge is mounted, check your electrical wiring by reconnecting the battery and turning the car to the “ON” Position. The gauge should light up and operate but not read anything as you have not connected the sensor nor started the car.

Now run the AEM UEGO sensor harness through the firewall and into the engine bay, as the Honda Fit’s exhaust is faced toward the rear of the car you can also opt to go through the shifter base or floorboard. When screwing your UEGO 02 into your midpipe, make sure to tighten snug and always make sure to secure the locking ring that snaps over the electrical connector on your sensor harness.



You’ve just finished the install of a wideband controller on your Fit! Happy Tuning!