Performance Trends, Inc.

Producing Quality Computer Tools for Racers and Engine Builders since 1986

A/F Checker to Verify Lambda/O2/Air-Fuel Sensor Accuracy



Our A/F Checker lets you check the accuracy of your A/F measurements by producing an exact A/F ratio, and then seeing if your A/F sensor reads it correctly.  You supply propane (like from an outdoor BBQ tank), and shop air at about 60 psi, and the Checker's adjustment knob lets you dial in most any A/F mixture from 9 to 17.  This lets you check your entire system, from the sensor through the electronics, logger calibration, the works.

Features include:

  • Large digit, backlit display.
  • Range from 9 to 17 gasoline A/F (or the equivalent in other units).
  • Readings down to 0.1 A/F resolution.
  • Rezero button.
  • Options for various features, including:
  •     Calibration info.
  •     A/F units for other fuels, including gasoline, E85, methanol, ethanol, propane/LPG, CNG, and lambda.
  •     Backlighting and power saving.
  • Battery powered with USB cable included for recharging.

The graph below shows how various good versus bad sensors read the A/F mixture produced by the checker.  You will see a new sensor follows the pink line very well.  The pink line is what the A/F checker readout shows.

You will also see that the used sensors, which were suspected of being bad, compared to the checker.  They were off by as much as 5 A/F or so, and did not even continue to read richer as the mixture was richened up.   

Obviously a really bad sensor will likely just be locked in on 1 particular A/F, and will not change its reading.  This situation is obvious.  But when the A/F does change with changes in mixture, you could be led to believe  your system is working correctly. Without the A/F Checker to verify your system, you do not really know if your A/F measurements are accurate.


More Info:

for movies of the A/F Checker in operation.

for the instruction booklet for the A/F Checker.


To Order:

for prices.

Call 248-473-9230. Visa and Mastercard and other payment methods accepted.

Electronics like the A/F Checker have a limited 1 year warranty.