Haynes manuals are a must for the car DIY-er. But beware! Every manual seems to have problems and this is no exception. A routine job (timing belt and water pump replacement on a 1.6 8V Picasso) almost became a nightmare. First, Citroen advise the use of an electronic belt tensioner costing £350 (Hello! DIY?) and a special valve compressing plate (neither of which garages seem to use!) Try getting (or, as Haynes advise, making) one of those compressing plates! Haynes, fearing litigation, dutifully repeat the advice. Just ridiculous! But then it gets worse, Haynes says that water pump replacement is an engine removal job as the pump is virtually inaccessible. Absolute nonsense! On the 1.6 8V the pump stares you in the face, almost inviting you to remove it! Imagine removing the whole engine on Haynes advice only to find it was totally unnecessary!
(Haynes made a similar error in removing the heater matrix in a Volvo 940)
Rough idling is a common problem on most modern cars with high mileage and the idle valve stepper motor is often the culprit, yet Haynes do not even mention this in their fault-finding chart and in the 'Fuel' section simply explain how to remove and replace the motor, with no mention of why you might need to do this; nor is there a photo showing its location.
Photos are a constant gripe. Apart from an absence of some quite essential photos, those available are often poor and fail to show location properly. (Try finding the flywheel locking hole in the cylinder block!)
The problem is that evidently Haynes do not get manufacturer-trained mechanics to review their manuals and weed out these errors or limitations.
So the manuals are necessary but often not sufficient. And, as in the above examples, they can be a downright liability!
My advice before starting what seems to be a big job, is to scour internet blogs, bearing in mind that they too can be misleading.