I appear to have typical VSS problem (I will check error codes), but in the meantime I'd like advice regarding possible ramifications of not fixing it.
Symptoms are: Speedo needle drops to zero and D4 light flashes, problem is intermittent and no other symptoms.
I've driven it quite a few times like this. -'93 Accord 4cyl vtec 425,000 k's dead reliable and solid as a rock apart from this problem.

 

Any ideas on this? Are there any bad consequences from running with a defective VSS?

 

Just to be thorough, actually check the codes by shorting the service connector. The common diy thread on top of the gen tech help forum has a link describing how to do this.

The transmission may not shift at the correct points. If the senor goes completely out, then you may have more shifting problems. When you have the speedometer drop out, does the cruise control work?

 

Sorry for the delay in replying.
Took it for a 50k run today. No speedo, blinking D4 light, no other symptoms, -It drove fine, but as you suggest, cruise control didn't work when the speedo didn't. Engine warning light came on and off 'sometimes'. Later, the speedo came back, then the cruise worked.
Yes I know I'll need to check the service connector (but I'm avoiding it 'cos I know I'll stuff my back up when I do it !!!!!)

 

The connector is behind the kick panel under the glove box. I think that you should be able to access by sitting outside the passenger door and leaning in. There are some youtube videos showing the location of the service connector.

Your symptoms sound like a problem with the VSS. Replacing it will likely fix your problem. I think you can get better access by removing the intake tube from the throttle body. The sensor sits on the transmission in the general area below the distributor/intake tube. I'm sure there are videos about replacing that too.

 

Thanks for your advice PA, I'll check it out. (I assume the service connector will be behind the driver side kickpanel in my (Aussie RHD) case.