volvo 240 air mass meter

Back a few months ago we had the engine warning light come on and the
diagnostics was showing error code 1-2-1 which is a fault in the signal of
the air mass meter.
We replaced the air mass meter and the code was gone.
Now it is warning us again with the same fault code 1-2-1

I really don't think we are going to be that unlucky to have two faulty air
mass meters, so I am wondering what else can go wrong with the air mass
meter system that can give that code?

 

Perhaps there is a less than tight and clean connection between the
wiring harness and the AMM.

 

I think we have sorted it actually now. Cleared the codes via the console
and its gone. Last time we didnt clear the codes and it seemed to go, but
obviously we did not do it properly.
Thanks for your reply anyway

 

Is the preheat tube thermostat in the airbox stuck open? That'll kill an
air mass meter quickly, for that reason I usually rip out the useless
preheat hose any time I work on a 240.