As enthusiasts we rely heavily on our car’s gauges to tell us what’s going on at any given time. If something goes awry, ideally we’ll spot such a problem in enough time to correct the issue and save ourselves the headaches that can come with damaged parts.

AEM Wideband Failsafe Gauge PN 30-4900

  • Displays both boost or vacuum and AFR or Lambda simultaneously on the same gauge
  • Internal boost sensor
  • Bosch Wideband UEGO sensor and weld-in bung included
  • On-board 3 hour data logging capability at 20hz per parameter
  • Full color Organic Light Emitting Diode (OLED) Display in center, user selectable feature (boost/vacuum or AFR)
  • Intuitive set up software
  • No free air calibration required
However, when you’re making a full throttle pass down the dragstrip, or even just trying to merge into rush hour traffic, it’s hard to keep a vigilant watch on those gauges. Under these type of circumstances if you were able to spot a problem couldyou adjust quickly enough to accommodate the impending issue?

We recently got our hands on a gauge that may help with just such a scenario. AEM Electronics, long known for their accurate gauge, data logging and computer control products sent us one of their Failsafe Wideband and Boost gauges.

This gauge incorporates both boost and wideband UEGO readings into one tidy package that still fits in a 2 1/16” gauge housing. It also has a data logging functions as well as several other features that we’ll get to in a minute.


We already had an AEM boost gauge installed in our 2011 Vortech blown “Wild E. Coyote.” However, this installation required some changes that those familiar with AEM’s gauges should note. The first being that this is a mechanical boost gauge, where we were before utilizing boost pressure sensor to feed input to our gauge.

Second is that the gauge harness in this case is different than the company’s typical digital gauges. This necessitated the installation and routing of a new harness.

Left Photo: our new Failsafe gauge takes the place of our old boost gauge. Right Photo: The failsafe gauge (pictured right) uses a different harness than most AEM digital gauges like our old boost gauge (left) requiring us to wire this new gauge properly before we can use it

This gauge also features data logging. Since we’re going to be installing an AEM AQ-1 in a later article, we ran the data logging wires under the driver’s side kick panel and sill trim and back to that unit. We have yet to connect the alarm feature or RPM wires. We also installed the included Bosch wideband UEGO sensor in our X-pipe and connected it to Failsafe. This wideband sensor does not require any “clean air” calibrations. This means you won’t have to periodically remove the sensor from your exhaust system to perform a calibration procedure.


Left to Right: We installed the new gauge in the A-pillar in place of our AEM analog boost gauge. This gauge uses a mechanical boost signal instead of digital, so we Teed into our AEM water/methanol controller's boost reference line that was already installed. The data logging wires were run along the driver's side sill and under the driver's seat, in which we will be installing an AQ-1 data logger on a later article. We also installed the Bosch UEGO Wideband sensor in our X-pipe.


AEM includes software for connecting this gauge via USB to a laptop or PC. This software will allow users to setup both the alarm functions as well as configure how the gauge displays information. It is important that when you setup the alarm and failsafe features that you already know what parameters will be used to trigger these features. In many cases your tuner should have an idea of a safe operating window for your car’s configuration and when those windows are exceeded the failsafe should be triggered.

Using AEM's supplied software the gauge can be conected via USB. In the Configuration tab users can setup the alarm/failsafe functions of this system.

Setting Alarm/Failsafe Trigger

The gauge configuration tab allows users to setup how they receive their data. AEM includes a wide range of silver and black gauge faces to to customize the outside sweep portion of the gauge.

The Failsafe Wideband and boost gauge has a trick feature that not only will provide driver’s with a visual alert when triggered but also can trigger a ground signal to help prevent problems; boost or timing retards come to mind as ideal candidates for this function. Many computer systems can also be configured to receive this signal and in turn run a failsafe strategy. This type of function could potentially save you thousands of dollars in ruined parts should such the need arise.

Alarm features can be set once a baseline air fuel ratio has been established by downloading the data from the gauge’s data logger function and configuring the alarm point on the graph. Users will configure a high and low point, AEM includes detailed instructions for setting this function up.

Once the alarm points are setup, test drives should be performed to ensure that the function does not trigger falsely and that it works accurately. False alarms can occur during shifts, sudden changes in acceleration like going from cruise to passing or other conditions.

The software features an adjustable delay setting that allows the end user to set an alarm delay, for example say the system sees an extreme lean condition during fast shifts like what may occur during a drag race. This lean condition may only be a flash in the time the clutch is engaged and the shifter is moving. A delay could be set to compensate for this so that the alarm and failsafe are not triggered causing unwanted effects.



The gauge features an LED lit sweep on the outside of the face with a digital display in the center. Like all AEM gauges the faces can be replaced with either black or silver, as well as black or silver trim rings.

Unlike many other gauges the data displayed and how it’s displayed can be configured for this gauge, again using the provided software. In the gauge configuration tab users can select the whether the LED sweep indicates boost or air fuel ratio or lambda and vice verse for the digital display. This type of configuration allows anyone using the gauge to configure so it’s easily understood at a glance to them. Further customizable features include the range for the analog LED bar graph, units of measurement and dimmer settings as well as alarm flash speed (fast or slow).


While the Wideband Failsafe comes with both air/fuel ratio standard on the in and outside read outs, we configured our center digital gauge to read vacuum/boost.

In the old days all we worried about was reading our gauges. Today enthusiasts are bombarded with more information than ever. Infotainment systems, smart phones and other devices all demand our attention. We like the idea of simplifying things a bit by combining two gauges into one easily read, customizable display.