My check engine light comes and goes. Went to AutoZone to have codes read. Was told the B solenoid in my transmission was what was triggering my check engine light. Being an intermittent problem, is there a way to test this solenoid? Or something common to the B solenoid that causes it to trigger the check engine light? Or is it something you just replace. If it's something you just replace, should I do the A solenoid at the same time. My Vitara has 195,000 miles on it.

Your transmission is electronically shifted (controlled by a computer), the solenoids are electrically operated valves that allow the computer to control when the transmission shifts, there are different codes for different issues, and you need to know which of the codes you're getting to be able to diagnose where the problem lies.

The actual problem can range from a defective solenoid, wiring or the computer itself, to blocked passages in the valve body of the transmission or other internal issues in the transmission