i have a 98 civic lx bone stock. i drove it from az to chicago. it ran good the hole trip and a few weeks after that. a few mornings ago i drove the car and it started getting hot right away thought the thermostat was sticking because no heat, than finally the heat started blasting and the temp came down. it was doing this off and on the ride home. so i went to auto zone and got a new thermostat and i was gana replace the temp switch also cause it seemed like the fans were being funny. i got home went to change the temp sensor and auto zone gave me the wrong one so i put the old one back on and changed the thermostat. i disconnected the battery because i was gana change the sensor. i hooked it back up and went to start the car. and all it would do was turn over. the CEL and d4 is flashing at me and the main relay is clicking like mad. the car was running great befor this. it is stock with 177,000 miles and 4 door. i changed the main relay the ecu checked the fuses all the grounds i could find and nothing will get it to start. i have fuel pressure. the injectors check good. i have spark. my buddy came with his testers and we cant find whats wrong. and both of us have obd2 code readers and neither will link with the computer to read the codes. and the morning i bought the parts i had auto zone run them and they pulled up an evap code but now no codes can be run it just says no link. PLEAS HELP ME!!! im going nuts and cant aford to take it in. im a decent hobbyist but im stumped.

 

ok so if any one has this problem i finally fixed it!!!! the main relay was clicking like a sob just click click click ect. the obd2 code reader couldnt link with the ecu. no it wasnt the ground at the thermostat housing which is what i thought. so when it tested to be a good ground i was wtf. so long story short it was the fuse box under the hood. the fuses are all good but the connecter on the bottom came loose. and presto days of agravation and making my self look bad and now im a hero.