In my opinion, Haynes has cheapened its manuals to try to cover more years and models with the same basic manual. Theirs used to be the best aftermarket manual. Chilton manuals are much improved and more comprehensive than they were back in the 1970s-1980s. Clymer manuals were much like Chilton's. (Typical Chilton or Clymer instruction for engine overhaul then: "Step 1. Remove engine." Uh, can you break that down a little? I'm exaggerating only a little.
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The factory manual plus at least one good aftermarket manual is the way to go. In my experience, finding information about specific procedures in the factory manual can be a headache. You have to be familiar with the manufacturer's specific nomenclature for particular parts. Some import factory manuals, especially for older cars, do not cover the procedures you would think they should.
For newer cars, you might find that most procedures are covered in the standard manual, but anything involving the engine electronics and emissions system, including OBD II "Check Engine" codes, will be in a different and far more expensive manual. This is true for Fords, for example. The factory service manual for all but the engine control and emissions systems was $100 for my Escort, but the engine control and emissions manual was nearly $200. Needless to say, I don't have the latter, and it never comes up for sale on eBay.
That's where a good aftermarket manual can help. The Haynes and Chilton manuals for my car largely cover what the standard factory manual doesn't, including OBD II codes.