AEM X-Series Wideband UEGO AFR Sensor Controller Gauge

Real-Time AFR Data You Can Trust on Every Run, in Every Build

The AEM 30-0300 X-Series Wideband UEGO AFR Sensor Controller Gauge combines AEM's X-Digital technology with a Bosch LSU 4.9 wideband oxygen sensor to deliver fast, accurate air-fuel ratio readings in a 52mm gauge housing. The AEM 30-0300 reads from 10:1 to 20:1 AFR (0.68 to 1.36 lambda), making it suitable for naturally aspirated, turbocharged, and supercharged applications running gasoline, E85, or other fuel blends. The X-Series design displays both AFR and lambda simultaneously, so tuners and builders can monitor the numbers that matter for their specific application. Universal fitment means the 30-0300 works with any vehicle, dyno, or test bench with an available 18mm exhaust bung location.

Key Features

• AEM 30-0300 X-Digital technology delivers fast response and accurate AFR readings across a 10:1-20:1 range
• Bosch LSU 4.9 wideband UEGO sensor included for precise oxygen partial pressure measurement
• 52mm gauge housing fits standard A-pillar pods, roll cage mounts, and gauge panels
• Simultaneous AFR and lambda display on the X-Series backlit face
• Reversible black AFR/Lambda faceplate lets the 30-0300 display either unit at the user's preference
• Analog output (0-5V) for datalogger and ECU integration
• Compatible with gasoline, E85, methanol, diesel, and other fuel types
• Includes weld-in O2 bung for permanent sensor installation

Specifications

What's Included

• 1 AEM 30-0300 X-Series wideband UEGO gauge
• 1 Bosch LSU 4.9 wideband oxygen sensor
• Sensor harness and gauge wiring harness
• Black gauge bezel
• Reversible black AFR/Lambda faceplate
• 18mm weld-in O2 bung
• Instructions

About AEM Performance Electronics

AEM Performance Electronics has developed aftermarket performance electronics for over 30 years. Based in Hawthorne, California, AEM produces wideband controllers, standalone ECUs, boost gauges, and data acquisition systems trusted by professional race teams and performance enthusiasts worldwide. The X-Series gauge line represents AEM's latest generation of X-Digital display technology for fast-response, high-accuracy sensor monitoring.

Frequently Asked Questions

The AEM 30-0300 uses the Bosch LSU 4.9 wideband UEGO sensor, which is one of the most widely used and trusted wideband oxygen sensors in performance and motorsport applications. The sensor is included in the kit.

The AEM 30-0300 reads from 10:1 to 20:1 air-fuel ratio (0.68 to 1.36 lambda), covering the full operating range for gasoline-fueled naturally aspirated and forced induction engines, as well as E85 and alcohol-blend applications.

Yes. The 30-0300 includes a 0-5V analog output that connects to external dataloggers, standalone ECUs, or piggyback fuel controllers that accept a wideband input voltage signal.

The AEM 30-0300 is the standard X-Series wideband gauge with wiring harness connection. The AEM 30-0334 adds an OBDII cable that allows the gauge to also read and display live engine data from the OBD2 port on the vehicle without a separate scanner.

Yes. The AEM 30-0300 is compatible with E85, gasoline, methanol, and other common fuel blends. The gauge reads in AFR and lambda, so the user can apply the appropriate stoichiometric AFR for the fuel type being used.

Yes. The AEM 30-0300 kit includes an 18mm weld-in O2 bung for permanent sensor installation in the exhaust pipe. A bung should be installed by a welder before running the sensor permanently.

The AEM 30-0300 can function on diesel engines, but the stoichiometric AFR for diesel is different from gasoline. The gauge will display real oxygen partial pressure data, but interpreting AFR numbers for diesel tuning requires understanding the different lambda targets compared to gasoline applications.

The AEM 30-0300 fits any standard 52mm gauge opening, including A-pillar pods, gauge panels, mounting brackets, and custom dash panels that use the common 52mm metric gauge size.

Installation Instructions

1. Select an exhaust location for the oxygen sensor bung, typically 18-24 inches downstream from the last exhaust manifold collector, before the catalytic converter for best response.
2. Weld the included 18mm bung into the exhaust pipe and allow it to cool.
3. Thread the Bosch LSU 4.9 sensor into the bung and torque to the sensor manufacturer spec (typically 40-45 Nm).
4. Route the sensor harness to the gauge location, keeping it away from heat sources above 200 degrees Fahrenheit.
5. Mount the 30-0300 gauge in the 52mm gauge location.
6. Connect the gauge wiring harness: 12V key-on power, chassis ground, and sensor harness connections.
7. If connecting the 0-5V analog output to an ECU or datalogger, route and connect the signal wire as required by the logging device.
8. Turn on the ignition, allow the gauge to calibrate for approximately 30 seconds before the first reading, and verify AFR is displayed.

WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.