astra ecu fault code 24

hi all wondering if anyone could help me i had fault code 24 on my
astras ecu i put a new speed sensor on well actually i have now tried
four and with each and every one of them the same code comes back on
just a few miles up the road and i have reset the ecu unit it is really
doin my head in now any help or ideas much appreciated thanks

 

What age/ engine are we talking about?

 

I presume your speedo is working ok.
Where is the sensor you have replaced and what does it look like? Is it the
one on the gear box that the cable goes into or is your speedo the type that
doesn't have a cable?

 

Have you done a continuity check to see if the wiring is ok back to the ecu?
You could also have a look in the big multi plugs behind the kick panel at
the near side front.

 

If you have checked wiring/plugs and your speedo works ok it leaves speedo
itself or ecu.
I will try to find a wiring diagram to look at tomorrow.

 

Wire goes from the speedo ( red/blue terminal 3) and goes to the ecu -
terminal A10. It goes through a couple of plugs on its way. X21 is a 16 pin
one and X9 is a 6 pin one. Have a look in the drivers kick panel. There is
also a feed to the info display.
Drive the car and get someone to press both the display buttons at the same
time - do you get a speed reading?