What is a common troubleshooting step if there is no signal on a pulse oximeter?

A common troubleshooting step when a pulse oximeter shows no signal is to ensure proper placement of the probe. This is crucial because the accurate detection of oxygen saturation levels depends on the probe being positioned correctly on a suitable site, such as a finger or earlobe. If the probe is not making good contact with the skin or is misaligned, it may not be able to effectively measure the light absorption by the blood, leading to a lack of signal.

Proper placement ensures that the device can effectively detect the amount of red and infrared light that passes through the blood vessels, which is how it calculates oxygen saturation. If the probe is loose, incorrectly positioned, or placed on a site with poor circulation, it can result in inaccurate readings or no reading at all. Thus, checking probe placement is a fundamental step in troubleshooting before considering other options.