Can I see OBD2 engine gauges on CarPlay?

Yes, with a Bluetooth LE or Wi-Fi ELM327-compatible OBD2 adapter. On the Live tab you can show up to eight stats, mixing trip stats with engine readings such as RPM, engine load, coolant and oil temperature, fuel level, throttle, battery voltage, airflow, fuel rate, economy and the check-engine light. The OBD tab adds connection status, this session's peaks, live readings grouped by system, your custom readings and trouble codes, which are read automatically when the adapter connects. Clearing codes is done on your iPhone. Set up the adapter once on your iPhone; after that it reconnects automatically whenever CarPlay starts. Which readings appear depends on what your car reports.