My truck was overcooling for who knows how long before I got it because a previous owner installed the thermostat backward.

it's fixed now, and running at a good temp... but what should I check that this condition might have damaged.

I've heard it could foul the oxygen sensor, and I assume it could damage the cats... anything else I should look for?

 

How would it become overcooled in the thermostat were installed backwards? It shouldn't have damaged anything anyhow. BUT, I'd disconnect the battery for a good 15 minutes, then reconnect it so the ECM can relearn everything.

 

well, I assumed the water pressure did it, but when I pulled it out, the thermostat valve had been unseated and pushed sideways leaving it open continuously.