Best thing is to download the S&S Pro Tune Software, pick the right matching USB cable and connect it to the ECU, which is sitting under the cover of the fuse box. You need a little torx tool to remove the little metal cover protecting the USB connector.
Ignition must be switch on to be able to access the ECU status, but it is not necessary to have the engine running. Check for the reported DTC's (engine trouble codes) and note them down. You may delete the errors, but the software must be first switched into Expert/Advanced mode, otherwise you can just review but not delete the trouble codes.
Then switch off ignition and check, if they are popping in again after switching ignition on again (if everything is ok they should be switched off after a couple of seconds).
For advanced users with some good basic understanding Pro Tune is offering a live monitoring mode, which allows to check all relevant engine parameters while the engine is running. There are a lot of field which can be added to get a better idea about the whole situation.
Keep in mind that all values are just values which are "seen" by the ECU. They might be bogus in case of sensor or wiring problems. In doubt you will need to find someone who is able to measure the real values to proof where the problems is caused.
