What is code 59 for the chevrolet malibu?

On the Chevrolet Malibu (and all other General Motors vehicles -- Chevy owners, take note!), OBD2 fault code 59 indicates that the transmission fluid temperature sensor circuit returns a high voltage error. This typically causes the check engine light to illuminate, so if it's an issue, Your Malibu will let You know. In almost all cases, the issue is the transmission temperature sensor, since this is the first line of defense against the code. It's also possible that a wire or wiring harness has failed, but this usually manifests as total failure and not a high voltage error. Luckily, these can be purchased for under $20, but they're a bit of a pain to replace; block out a few hours, grab a beverage, and dig in.