OBD1 ECU Wideband Installation Wiring Instructions

There are many different ways to wire in a wideband oxygen sensor. From our experience, many methods cause poor wideband sensor performance due to electrical interference or insufficient grounds.

The following method for wiring in a wideband oxygen sensor to a vehicle equipped with an OBD1 ECU is our recommendataion for the cleanest install, quickest install, and the best signal from your wideband sensor to your ECU. This will provide an accurate 0-5v output that can be datalogged using Crome Pro, Neptune RTP, or Hondata S300. If you are using our eTune service with Crome Pro, Neptune RTP, or Hondata S300, then this is the way you should install/wire your wideband.

First, remove your stock O2 sensor and replace it with your wideband O2 sensor. Route the new wideband sensor's cable/wiring through the firewall and down to your ECU area. Be sure to use caution when selecting a location on the firewall to route the wires through. Use a grommet or other method to insulate the wiring so it does not get cut or damaged.

Second, you will be making the connections to your ECU's wiring harness for the wideband's power, ground, and 0-5v signal output. Make these connections close to the ECU, 3-6 inches from the ECU connectors is perfect.

Strip approximately 3/4 inch of insulation off of the wire going to pin A25. This wire should have +12v with the key turned to the "on" position. Solder your wideband's +12v switched power wire to this wire and either cover with electrical tape or heat shrink.

Strip approximately 3/4 inch of insulation off of the wire going to pin A26. This wire should have continuity to ground at all times. Solder your wideband's ground wire(s) to this wire and either cover with electrical tape or heat shrink. Some widebands have more than one ground wire. If your wideband has multiple ground wires, connect ALL of the ground wires to this same location.

Cut the wire going to ECU pin D14. This is your O2 sensor signal wire. Tape off or heat shrink the wire coming from your vehicle's side of the harness and tuck to the side. Connect/solder your wideband's 0-5volt output/signal wire to the wire coming from pin D14 and either tape or heat shrink the wire to protect it.

You can now read an accurate wideband signal through your ECU for datalogging with Crome Pro, Neptune RTP, or Hondata S300.