If the SRS light remains out then great. However, code 5 indicates a bad or missing ground for the driver airbag, which is referring to the entire airbag circuit. The same code is raised for a break anywhere in the wiring as well as for an open connector. Although the problem could be a weak electrical connection at the gas generator (240s are great for grounding issues), I think it's much more likely to be a broken clockspring, also known as the contact reel, a term commonly used by Volvo for 240 SRS. Normally the spring conductor completely breaks, but old ones can also have an intermittent break in the spring circuit before they finally break.

If your SRS light comes back, please reply in this thread or start a new post. I've got notes available with complete step-by-step DIY information on diagnosing a bad clockspring, removal and replacement, complete with p/ns and specifications. Do not attempt to remove the clockspring until you understand some of the subtleties, most notably locking/unlocking the clockspring and always resetting the neutral position. Videos are also available online of assorted quality to give you an idea of the project.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now