If you are investigating a high idle just after a cold start, save every stored and pending code before clearing anything. Look at coolant temperature and commanded idle only after the engine has been sitting long enough to cool. Record the engine temperature and load alongside the reading; the same value can mean different things in different conditions.
A basic reader may not access every module. Compare behavior with the owner’s manual and check for an intake hose left loose after service. Use the exact vehicle’s service information to interpret the result.
Quick educational note
For information, not a diagnosis or repair instruction. Vehicle-specific checks are still required. Consult the manufacturer's guidance and a qualified technician.
How to use this information
This article explains general principles and does not establish what is wrong with your vehicle. Read the content limitations.