well, its very easy to hit a wire down in that area... the ECU is right there, so theres a ton of small wires and they tend to run in places you wouldnt expect.

If for some reason you may have been tinkering around near the passenger side of the engine block, its possible that you broke off the connector for the temperature sensor, they're pretty fragile.

Have the check engine light diagnosed by auto zone or another parts store, hopefully the car dosent catch fire on the way there.