...but there's no CEL, and I don't have a 4,500 rpm rev limit either. It's an MY93 WRX (analogue speedo).

I've checked that the cable is attached to the dash (it is) and the cable seems to be intact.

I've also checked the CEL codes and I have; "lambda sensor" (irrelevant, because there's no lambda fitted at the moment) and "idle control system", which I believe is because of the engine revving when off throttle while engine braking.

With these symptoms, is it likely that the dash speedo is broken? I'm a bit confused, because when the speedo stopped working previously (the step-down gearbox broke) I had the rev limiter, but this time I don't, leading me to suspect the dash, rather than the cable.

 

I've had this and it was the cable from the converter to the back of the speedo head it was flopping about in the engine bay.

I've had quite a few break on me (the odometer mainly) so go myself a bit of metal filed down to fit to go inside the plug where the cable goes and spin it to (using a power drill) that picks up the speedo needle working to put miles on the odometer

 

What turned out to be the problem with this mate?
This is the exact same problem ive got with exactly the same error codes as well

 

its a process of ilimination if you pop the hood thn disconect the speedo cable where you would put your delimetre/ mph converter.
then attach a power drill to the cable leading to the speedo head and run it as you watch the speedo you should get bout 160.
if that happens the speedo head is fine.
the connection on the speedo cable under the hood is very sustainable to rattling out if the clips arnt bang on then youl get nothing .
hope this helps
nathan