Toyota Repair: engine check light, vehicle speed sensor, digit code number

Question
QUESTION: i have a 1994 toyota corolla sedan 1500cc 5afe engine whenever its cold and its driven fast the engine check light doesnt come on but as soon as the tempature reaches a little under half and the car is being driven fast the light comes on and stays on until the car is turned off

ANSWER: The tropuble code in the computer should be retreived first, this can be done by connecting a jumper wire under the hood to the diagnostic check connector between terminals TE1+E1, with the key on the check engine light will flash a two digit code number, for instance a code 25 would be two blinks of the light followed by five, can you let me know what the code is so I can help?

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QUESTION: the code i retrieved is 42  but i checked past answers on  the same code and the problem was the speedometer sensor. my speedometer isnt working but isnt the check light supposed to come on as soon as the car begins to move if it is the speedometer sensor ??? and in my first question i mentioned when it reaches a certain temperature the light comes on. what does the temperature has to do with it???

Answer
Not necessarily, here is the description from the factory service manual  ("SPD signal is not input to the ECU for at least 8 seconds
during high load driving with engine speed between 2600
rpm and 4500 rpm.") I think the obvious needs to be fixed first which would be to replace the vehicle speed sensor.