How to Read Compound Monitors

Some monitors are simple and easy to understand. They are the direct result of a sensor output (such as Manifold Absolute Pressure) or they are the result of a request or calculation of a table (such as a requested torque value). These monitors are essentially telling you one thing and typically easy to understand what the value means.

Compound monitors are when there are multiple checks shown in the same monitor. These checks are each assigned a value, then added together to get the final monitor output.

So that there’s some basis for the explanation, let’s look at the Launch Control State monitor for VW vehicles (LC State). The values are shown below.

As an example let’s say the value being output is 3

We now look and see what two monitors added together equal 3

In this case we see that

Launch Control Disabled =1
Oil Temperature Disabled=2

So both of those warnings are being given.

Obviously this can get a bit more complicated to math out given that there are numbers in the tens of thousands. While you can sit there with a calculator and start subtracting numbers until you get an even zero at the end to figure out which ones are active. We recommend you use an online calculator or even the basic windows calculator in programming mode.

The Easy Calculator (Internet Required)

If you have access to the internet, a bit calculator such as this one https://www.miraclesalad.com/webtools/bit-calculator.php makes it fairly simple and will directly highlight the bit value for each monitor.

In this example our monitor value of 49742 was easily decoded to be the values in red (2, 4 , 8, 64, 512, 16384, 32768)

Windows Calculator (Advanced)

For an alternate (and slightly more complicated) option you can use the calculator app found in windows and click the three lines on the top left to change it to programmer mode.

Make sure to select DEC (decimal) and the bit toggling keypad

Now when you put in a number you can see some 1’s start to show up below

Each one of those columns is going to be a bit position as seen below

So in this case a 1 in the position means the corresponding monitor is active.