Wideband AFR Gauges

Is your engine running too rich or too lean under load? A wideband AFR gauge shows the air/fuel ratio in real time, so you can monitor the mixture while tuning, on a track day or in everyday driving with a modified engine.

What does a wideband AFR gauge show?

A wideband oxygen sensor in the exhaust measures the oxygen content, and the gauge converts it into an air/fuel ratio. A conventional narrowband sensor typically only shows whether the mixture is rich or lean around the stoichiometric point, while a wideband gauge can display precise values over a wider range, e.g. 8:1-18:1 or 10:1-17:1 depending on the model. This makes it easier to spot a lean mixture, which can raise combustion temperatures when you increase boost or change the fuel injection. The category includes gauges from AutoMeter, and many combine them with fuel pressure and oil pressure gauges.

How to choose an AFR gauge

• Analog or digital: electric analog gauges with full sweep electric (FSE) pointers, e.g. in the Ultra-Lite II, Cobalt and Sport-Comp series, or digital display as in Phantom and Z-Series.
• Measuring range: choose a scale that covers the values your project typically works with.
• Size and design: the gauges here are 52 mm (2-1/16"), so choose a series that matches your other individual gauges and the gauge pod you have room for.
• Sensor and installation: check for the specific part number whether the sensor and controller are included, and how the sensor should be positioned in the exhaust.

Frequently asked questions

Why choose a wideband over a narrowband gauge?

A narrowband sensor typically only shows whether the mixture is on the rich or lean side of the stoichiometric point. A wideband gauge can show the actual ratio over a wide range, which is more useful when the engine is tuned.

Where should the oxygen sensor be installed?

Typically in the exhaust before any catalytic converter and some distance after the exhaust manifold, so the sensor is not exposed to unnecessary heat. Always follow the installation instructions for the specific part number, as position and angle can vary.

Why does the gauge show unrealistic values?

This can be caused by a worn sensor, an exhaust leak before the sensor or faulty wiring. Leaded fuel, oil in the exhaust and condensation can typically shorten the sensor's lifespan.