Early O2 sensors are known as “Narrow Band” sensors as they can tell the ECU if the engine is rich or lean via their output voltage, but not by how much. As a loose rule, they have a maximum of 4 wires, one for the signal to the ECU and an earth for the sensor. The other two wires are a for a 12V supply for the heater element and a ground wire.

The fifth wire indicates the introduction of the “Wide Band” O2 sensor or can be referred to as “A/F” ratio sensors. These are more complicated and work on a principle of balance or equilibrium between two different sensing components. To do this, the ECU receives an oscillating voltage signal from the Nurst / Measurement Cell which is basically a narrow band O2 sensor, with exhaust gas in the measurement chamber on one side and the atmosphere on the other. On the other side of the measurement chamber is the Pump Cell, which can pump O2 in and out of the measurement chamber. The ECU supplies a reference voltage to the Pump Cell, and will vary the current required in the circuit to maintain a Lambda point of 1. By monitoring the voltage signal from the Measurement Cell, the ECU will adjust the current in the Pump Cell to keep the voltage signal from the Measurement Cell at a constant level. This balancing act gives the ECU an accurate and fast measurement of the amount of mixture adjustment that is required.
Tech Talk May 2017 page 4333.

MotorTech members have access to an extensive technical information resource, a Technical Advisory Service and library staffed by experienced technicians, along with a comprehensive online resource, Tech Online, Tech Times Guide, Tech Estimate and Tech Talk magazine, plus online resources from Haynes - Haynes Pro and Haynes AllAccess, allowing you to repair and service more makes and models than your competition.

To learn more: W: [ Ссылка ] T: 03 9829 1268 E: info@motortech.com.au


This video contains some useful tech tips but is not intended as a comprehensive how-to guide. For more information, VACC members can contact the VACC Technical Advisory Service.

Not a member? Find out how VACC can help drive your auto business forward!

Visit [ Ссылка ] or call 1300 013 341

Connect with VACC
LinkedIn: [ Ссылка ]
Facebook: [ Ссылка ]
Twitter: [ Ссылка ]
Instagram: [ Ссылка ]

свернуть