Owners Manual
The owners manual generally lists weights and capacities. What Fuel, Oil, etc you should be using etc. It also generally lists your service intervals; When you should perform certain maintenance tasks. Owners Manuals, given the intention of the publication are often available online at the Manufacturers website, or distributed by other websites.
If your manufacturer doesn't have your Owners Manual available try JustGiveMeTheD*&%Manual.com
Factory/Manufacturers Workshop/Service Manual
These are manuals "written" by the manufacturer specifically regarding the Platform(s)/Model(s) relative to your vehicle. These generally require purchasing, but as other users have pointed out, they are available online through some searching.
Third-Party Service Manuals/Guides
- As others have mentioned, Haynes or Chilton guides can be great for learning basic-to-advanced repairs. Mitchell and AllData provide even more advanced guides at the professional-level.
- These guides can sometimes be found at your local library. Both in physical copy and sometimes Online/Digital Resources, as well.
- AutoZone.com offers Repair Information, if you register with their site (Free). Your Local Autoparts store may offer a similar service, as well.
- YouTube, and other Video Websites, are a great place to watch repairs in action. Granted one can pick up a lot of bad habits, so use your best judgement when watching different methods.
- Model-Specific Forums are great for detailed and hyper-specific questions.
OBDII Code Readers
On-Board Diagnostics, Or OBD, offers access to varying amounts of data about your vehicle. You can, depending on the model, view (in real-time) things like Throttle Position, Coolant Temperature, etc. Some OBDII Code Readers have basic functionality which only allow for reading and clearing codes, while others have more advanced functions.
If you already have an Android and/or iPhone, you can use a OBDII-to-Bluetooth/Wifi Adapter coupled with software on your phone to view some of the advanced data that was mentioned earlier.
Given that you have a Check Engine Light on you will want to either acquire a OBD Code Reader and/or visit your local Autoparts store, as many will offer free code scans. Be sure to carefully write down what code(s) are found, and get back to us with the results, so we have a better idea of what's going on with your vehicle.
I hope this helps!