P1457 is a leak in the EVAP-charcoal canister system. The Helm manual has about 5 pages of things to check. There's the canister underneath the car, a 3-way valve, a couple solenoid valves, a filter, & a bunch of vacuum tubing.

Look for a solenoid valve on top of your intake manifold. Check for torn or disconnected vacuum hoses. It doesn't have anything to do with coolant, but maybe something got pulled off near the thermostat???

I got that same code last year, the guy told me I needed to learn how to tighten the gas cap... In my case it was a solenoid valve under the car. You'll need a MityVac & a couple jumper wires to check that stuff. I'll try to remember to look that up & summarize it. But you'll be much better off by getting yourself a Helm manual. (Public library??)

You can clear the code by pulling the #13 fuse in your right doorjamb. That way you don't need your radio code...

While I waited for the part, I cleared the code. It didn't come back for a couple days, so there's something about that system that doesn't record an error until it happens a few times.