Professional-Grade Lambda/AFR Monitor For Motorsports Engine Tuning

The AFX2 Lambda/AFR Monitor

The AFX2™ Monitor is the long-awaited upgrade to the industry-standard AFX™.  AFX and AFX2 were designed and are manufactured by ECM, the world's leader in Lambda instrumentation.  Over the years, tens of thousands of AFX were sold by NGK Spark Plugs (NTK), but they were really designed and made by ECM.  Now you can buy the new and improved monitor, the AFX2, for less, and direct from the manufacturer at

The AFX2 has all of the features of the AFX (i.e. AIR CAL feature and 0 to 5V output) with the following new features:


The module can display either Lambda or AFR (both for gasoline and methanol).


New wider range for the AFX2:
• 0.411 to 1.373 Lambda
• 6 to 20 AFR (gasoline)
• 2.66 to 8.88 AFR (methanol)

Original range on the AFX:
• 0.618 to 1.098 Lambda
• 9 to 16 AFR (gasoline)
• 4 to 7.1 AFR (methanol)

* Both ranges are selectable via an on-board jumper


Supports Bosch LSU4.9 and LSU4.2 sensors and NGK Spark Plugs (NTK) non-cofired sensors.


The AFX2 features faster display and analog output updating.

User's Manual

We wrote the original AFX User's Manual.  The AFX2 manual is based on the AFX manual with a few tidbits of wisdom inspired by hearing from users over the last 10 years.

Unlike 10 years ago, there is a wealth of information available today explaining how to calibrate engines.  The books and CDs written by Greg Banish ( are excellent examples of this.  Attending one of Greg's seminars is a rare opportunity to be trained by an engineer with extensive automotive OEM and aftermarket calibration experience.

What's Included

When you order the AFX2 Kit, the following items will be included:
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Display Module

P/N: AFX2_Display
The display module is compact, yet easy to read.  The calibration knob and analog output is accessible on back of the module.
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P/N: AFX2_4.9harness
The harness has a 13′ (4m) length to the power connections, a 13′ (4m) length to the sensor, and 4″ (100mm) long analog output wires.

The AFX2 Kit is NOT Supplied with a Lambda Sensor

The reason why is that there are currently thousands of used but good Bosch LSU4.9 sensors in automotive wrecking yards that you can buy for about $5 each and the AFX2 has the ability to check out and recalibrate these sensors.  All LSU4.9s have the same connector.  Bring your AFX2 to the yard with a motorcycle battery to test the sensors.  If the AFX2 doesn't show any trouble codes for the sensor and the sensor calibrates, you can use it.  So for the price of a new LSU4.9 sensor, you can buy a lifetime supply of perfectly good used sensors.  If you have an AFX, you can use its harness and sensors with the AFX2.  But if you want a new sensor, drive to your local auto parts store and buy the least-expensive LSU4.9 sensor they have (ex. Bosch P/N 17025).

Note: The thread on all wide-band lambda sensors is 18mm x 1.5mm.  Mounting bosses are widely available.

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Bosch LSU4.9

Bosch LSU4.9 sensors can be easily identified by having five wires and a gray ribbed wire sheathing.
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Bosch LSU4.2

A Bosch LSU4.2 sensor looks like a LSU4.9 sensor except the ribbed wire sheathing is black.  The Bosch LSU4.2 sensor can come with several different connectors and is being phased out by Bosch.  So unlike the LSU4.9, one harness will not cover all the LSU4.2s out there.  For this reason, a LSU4.2 harness is not offered.  However, the AFX2 User’s Manual explains how to make an adapter cable for any LSU4.2s and the AFX2 will operate with this sensor.
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NGK Spark Plugs

NGK Spark Plugs (NTK) has two families of wideband sensors, non-cofired (on left) and co-fired (on right).  Both have five wires and they can be identified by appearance.  The non-cofired has a longer portion sticking out of the exhaust pipe and a thinner body.  The non-cofired is the most common and the AFX2 will operate with it.  Like the Bosch LSU4.2, there is no standard NTK connector but you can use your old AFX harness (and sensors) or make an adapter cable for any non-cofired NTK sensor.  The AFX2 User’s Manual explains how to do this.

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