AEM UEGO Failsafe Wideband AFR/Boost Gauge

Part #: AEM 30-4900
( 1 reviews )


MSRP: $445.80


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Brand: AEM
Gauge Backlight Color: Multi Color OLED
Gauge Face Color: Black / White
Gauge Needle Color: Multi Color Sweeping LED
Gauge Range: 10.1:1 - 20.1:1
Gauge Sending Unit: Electrical
Gauge Size: 52mm
Gauge Type: Air Fuel / Boost
Requires Control Unit: No
Sensor Thread Pitch: Standard O2
Wideband Sensor Type: Bosch
Gauge Range Boost: -29inHG - 29.4psi (-1bar - 2bar)
Mfgr. Warranty: 1 Year
Return Policy:

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Items that are covered under the RallySport Guarantee offer a 30 day no questions asked return policy.

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The RallySport Guarantee does not apply to products that have been modified, damaged, misused or abused. All returns require an RMA (Return Merchandise Authorization) Number, and freight charges are strictly non-refundable. For more information regarding our freight refund policy, please refer to our return policy page found HERE.


Universal Product This item is non application specific.
Please verify compatibility before purchase. May require some modification for proper installation.

The Wideband FAILSAFE Gauge provides the ability to accurately tune AFR, while actively protecting your engine by constantly monitoring AFR curves and activating a user-defined failsafe strategy if it runs lean.

The Wideband FAILSAFE Gauge is a Universal Exhaust Gas Oxygen (UEGO—“you-way-go”) controller with an internal boost sensor, an internal data logger and a full color Organic Light Emitting Diode (OLED) display. It includes technology to activate a failsafe strategy in the event AFR falls outside of a user-defined operating window. If the AFR falls outside of the set operating window, the Wideband FAILSAFE Gauge triggers a user defined output function that can save an engine from catastrophic damage.

After the engine is tuned and a safe operating window of AFR is established, the Wideband FAILSAFE Gauge continually monitors AFR and boost or vacuum to make sure that AFR does not fall out of the defined operating window at a given boost or vacuum level. If the Wideband Failsafe detects an out of range AFR reading, the gauge triggers a low side output (ground signal with a 1.5 amp draw max) that can save your engine from catastrophic damage.

Use the gauge’s intuitive software to configure the low side output, create a user-adjustable time delay strategy to prevent false alarms, and customize the gauge lighting to flash and alert the driver if an alarm is triggered.

The system contains an on-board data logger for logging over three hours of data recording (20 Hz per parameter) of AFR, RPM, boost, alarm, and others. Data logs can be downloaded for viewing in the new AEMdata software.

The 52mm (2-1/16”) Wideband FAILSAFE Gauge includes a Bosch 4.2LSU AFR wideband sensor for monitoring and feedback of AFR and an on-board boost sensor to read vacuum or boost pressures up to 29 PSIG. Both boost and AFR can be displayed in real time on the gauge’s face using the full color OLED screen and 24 three-color sweeping LEDs. The gauge includes a low side output for triggering a failsafe strategy in the event AFR falls outside of the operating window, and an RPM input to log RPM for tuning purposes.
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Verified Purchase
Two gauges in one...and it'll save your motor.
otto51722705 2 years ago
This gauge has saved my motor on at least three occasions and really is the perfect solution for those looking for a boost gauge AND an AFR gauge. My only complaints are that the installation/setup instructions are pretty thin (a good tuner/calibrator is needed to take full advantage of the gauge features) and the boost gauge is limited to 30psi. I wish it was much higher.


  • AnswerQ: Bung  06stidd 5 months ago

    Can this go in the bung on the up pipe?

    • A: You will want to connect this to the bung on your downpipe, if you have the extra 02 bung. If you dont have one a exhaust shop should be able to create something custom for you.

      Trevor C. 5 months ago

  • AnswerQ: Gauge Dimming   organiclad3527444 6 months ago

    Can this be wired to dim with the stock gauges and interior? The description makes no mention of dimming of any sort, is it possible to dim it otherwise?

    • A: The gauge does have a dimmer wire which would be Pin 10 Gray *OPTIONAL* Gauge backlighting; connect to instrument lighting.

      Nick S. 6 months ago

  • AnswerQ: Single Pods  Shibikku 2 years ago

    Which single or mounted pod gives the AEM UEGO Failsafe best fitment? thanks!

    • A: This gauge will fit in almost any 52mm pod and it does not necessarily fit in one better than another.

      Zach G. 2 years ago

  • AnswerQ: Boost gauge accuracy  VLopatin 2 years ago

    Hello, have Defi boost gauge but need AFR and failsafe added. My concern is in boost sensor. With Defi I have very short analog boost line and then digital. With AEM I see that analog line goes directly to the gauge – so it can case delays and inaccuracy with boost measuring and problems with installation. Is that possible to use external boost sensor with that gauge (for instance AEM 30-2131-50 )?

    • A: Unfortunately these are not compatible with an electronic sensor however, there will be little to no delay and the readings will be very accurate.

      Spencer H. 2 years ago

  • AnswerQ: Single bung downpipe  pwatson13029 2 years ago

    Can this work with a single bung downpipe, aka replacing the stock O2 sensor?

    • A: This can but it is best suited in a bung of its own, located in the upper half of the downpipe, in the case this is going on a Subaru. Thank you.

      Sterling W. 2 years ago