Miata Turbo Forum - Boost cars, acquire cats. - Wideband O2 Install using Cigarette Lighter Power and Stock O2 Plug

When researching to install my wideband I saw a lot of conflicting information about what does/doesn't work. I wanted to share my experience as I believe it could be valuable to someone.

I was installing my wideband to use alongside a SpeedyEFI PNP unit for my NB1 (2000). One of my goals was to make the install as reversible as possible. I did not want to cut any of the factory wiring up.

The actual o2 sensor is in the factory location in the exhaust. I ran the signal wires up through the transmission shift boot and behind the radio panel, which is where my gauge is mounted.

For power and ground, I saw a lot of people saying that the cigarette lighter's power/ground wires would not work. My cigarette lighter was disconnected by the PO (I assume the fusible link in the lighter socket blew), so I figured it would be a good option to try. I crimped on some spade connectors and plugged them into the power and ground leads for the cigarette lighter. The gauge powered up fine, no issues.

For the signal wire, I ran the wire through the firewall and soldered it onto an extra 02 sensor plug I had laying around. This was the white wire from the gauge, to the signal wire on the stock harness. In theory, this allows me to simply disconnect the gauge from the harness and plug it back into a narrowband sensor if I needed to go back to the stock ECU. I have a Cali emissions car, so my signal runs to the plug at the front of the engine via an O2 extension.

I've been running and tuning this setup for about a month now and have had no issues with it. My AFR readings are consistent and don't seem to have any of the issues people have attributed to bad grounding in other threads. My readings at the gauge and on tuner studio track each other very well.

One of the segments on one of the 7 segment displays does keep coming in and out. I don't believe this is due to the wiring. I did buy my gauge second hand, although it was working solidly when I first installed the gauge. I assume it's an issue with the gauge, but figured it was worth mentioning.

This seemed like the most straightforward and reversible way to wire the gauge up in my situation. I didn't find many other success stories of people wiring their gauges this way, so I wanted to share. I'd be interested to hear other's thoughts on this as well.

TLDR : Wired wideband power and ground into the cigarette lighter wiring and ran the signal wire out to the factory plug in the engine bay.