I'd check the sensor. It's located at the front of the block, above the water pump, near the thermostat housing. There is a wire that comes off the wiring harness that feeds the injectors - I believe sensor wire is a red wire with a black elbow connector that plugs into the top of the sensor. The sensor is a stubby white cylinder about 2" tall. The connector on mine broke off and I did not get a reading. Try that.