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Air/Fuel Gauges
Air Fuel Gauges: Frequently Asked Questions
An air-fuel gauge, also known as an AFR gauge or ratio meter, monitors the air/fuel ratio of an internal combustion engine. It reads the voltage output of an oxygen sensor, which is sometimes referred to as an AFR or lambda sensor.
There are also ethanol gauges, which are designed to detect ethanol content via the sensor, which also measures fuel temperature.
What Do They Do?
The sensors of the AFR are linked to the voltage of the vehicle's computer system, which adjusts as necessary throughout a drive.
When the voltage reaches .450V, the meter will reduce the amount provided to the engine through the injectors. Some of the benefits of using an AFR include:
- Enhanced engine performance.
- Increased fuel economy.
- Reduced emissions.
- Determines the condition of the oxygen sensor.
Do I Need an AFR Gauge?
An AFR can tell you about the balance of air and fuel in the engine. It's extremely important to have this right, so that you aren't wasting petrol. It will also tell you if your engine is running correctly, if your ratio is in a safe range, and how well your car is running under all circumstances.
Wideband Gauges
These are designed to measure the ratio in a vehicle's internal combustion engine, and have been developed to deliver on greater accuracy compared to the previously used 'narrow gauge'.
Professionals swear by these and say they are a must-have, encouraging other drivers to install them so they can always know what's happening with the ratio when the car is on boost. You definitely need one of these if you don't want to blow the motor due to running lean.
What is the Best Air/Fuel Ratio?
Theoretically, the ideal ratio for complete combustion is called the stoichiometric ratio. The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all petrol with no excess air present.
For gasoline, the stoichiometric mixture is about 14.7:1. So, for every gram of fuel: 14.7 grams of air are required.
How Do I Know if My Ratio Sensor is Bad?
Generally, when your sensor begins to show issues, this is the car’s way of alerting you that an air/fuel ratio sensor may require attention. You may start to notice the following symptoms:
- Less efficiency: If there is any problem with the sensor, it can send a bad or false signal to the computer, which can throw off its calculations and cause excessive wastage.
- Rough idle: A poor or failing oxygen sensor can send an inappropriate signal to the computer, which may throw off the idle and cause it to fluctuate or drop below the correct level.
- Decrease in engine power output: If a ratio sensor has become ‘lazy’, it will send a delayed signal to the computer over time, which may result in an overall delayed response for the entire engine. As a result, you may experience a sluggish or delayed response when accelerating, as well as a noticeable loss in speed and power.
For more, check out our performance aftermarket kits and shop our range of gauge pods and boost gauges. Get in touch with the team at Pro Speed Racing today.


Prosport 52mm JDM Series Performance Gauge Range - Amber/White
RRP $99.95


Prosport 52mm BF Series Performance Gauge Range - Amber/White
RRP $99.95


AEM Wideband O2 Air/Fuel UEGO Gauge Kit (No Sensor)
RRP $249.95


Prosport 52mm Evo PK Series Performance Gauge Range - Red/Blue/Green/White
RRP $99.95


AEM X-Series Wideband UEGO AFR Sensor Controller Gauge with OBDII Connectivity
RRP $419.95


GFB Replacment G-Force 4-Port Boost Solenoid
RRP $162.00


Haltech WB2 Dual Channel CAN O2 Wideband Controller Kit


Innovate Motorsports DB Blue AFR Air/Fuel Gauge Only NO SENSOR


Innovate Motorsports DB Green AFR Air/Fuel Gauge Only NO SENSOR


Innovate Motorsports DB Red AFR Air/Fuel Gauge Only NO SENSOR


Innovate Motorsports ECB-1 Ethanol Content/Fuel Temp/Boost/AFR Advanced Gauge Kit


Innovate Motorsports ECB-1 Ethanol Content/Fuel Temp/Boost/AFR Advanced Gauge NO ECA SENSOR


Innovate Motorsports ECF-1 Ethanol Content/Fuel Temp/Fuel Pressure/AFR Advanced Gauge Kit


Innovate Motorsports ECF-1 Ethanol Content/Fuel Temp/Fuel Pressure/AFR Advanced Gauge NO ECA SENSOR


Innovate Motorsports LC-2 Wideband AFR Air/Fuel Controller Cable Kit w/3ft Cable


Innovate Motorsports LC-2 Wideband AFR Air/Fuel Controller Cable Kit w/8ft Cable


Innovate Motorsports LC-2 Wideband AFR Air/Fuel Controller Cable Kit w/8ft Cable NO SENSOR
Universal items are not application specific and may or may not suit your vehicle. Some items may be suitable but are listed as universal (ie wheel nuts, oil filters) and In some circumstances a product may not fit automatically but can still be used with some modification (ie. catch can/gauge pod etc.). Be sure to check if the product is right for you or ask us for assistance before purchasing. Filter universal products by selecting “Show Universal Products” from the filter products menu.