Ethernet shield increasing readings from TMP36 temperature sensor by 20 degrees

Hi,

I had a TMP36 temp sensor providing input into one of my analog inputs on my arduino. This setup was working fine, i had the code converting it into degrees f - all good.

I decide i wanted to send this data over a network, so plugged in an ethernet shield on top of the arduino and rewired my sensors back exactly as i did before. Now though the temperature, although still responsive, appears to be about 20f above where it was before at all times.

It certainly hasn't jumped 20f in the time it took me to wire the thing up. Please could someone help me understand what is going on, or adjustments I might need to make when using shields and sensors together.

Thanks for your help,
Adam