I have a 2007 Jeep Liberty Sport v6 with 4 wheel drive. It has about 82,000 miles. This week the check engine light came on. I used the scanner and it showed two codes. P0300 and P0304. I went to Auto zone and purchased new ignition coils and new spark plugs. After installing them the check engine light and codes were still registering on the scanner. I removed the negative terminal from the battery and that cleared the codes and check engine light. I went for a short trip to the store and now the temperature gauge is climbing up to the Hot range. It wasn't moving from the center of the gauge before this work. Could I have caused this or is this just another problem?