Hello everyone, first allow me to send out season greeting to whom reading this thread.

I recently let authorized dealer replaced my O2 sensor. And I thought it is a good idea to do the service.(oil change, air filter and oil filter change) So, I ordered them to do it. Since I love Miss Civic quite a bit, I decide to give her a treat to let her run on synthetic oil.
When I get the car back, I did not discover any problem at first. But after I drove around for a while, I found out the idle is high and when I stop the car at the traffic light, the engine speed will go up for a while and then come down. It seems to me like the engine is running rich. But I do not under stand why synthetic oil will change the engine behavior so much? Or there is other thing going on?
Another problem I found out is, it seems like synthetic oil will cause the engine light flash 7-8 time after turn on the master switch. Does that mean synthetic oil is more viscous to let the oil pressure built up?

By the way, Miss Civic was born in 2005 with manual transmission.

 

I think you should go back to the dealer that performed maintenance on the car and complain about it. Changing oil or oil type will not make CEL to come on,,,,,.
Re-setting ECU may solve the problem.

 

The CEL does not come off when the engine is running. But it will flash 7-8 time when the ignition key turn to standby(the position before and after start the engine) If the ECU really use O2 sensor's input for compensation. I may really need to go back to dealer to let them calibrate the sensor(Well, presumably all O2 sensors should be calibrated prior they leave the factory.)

 

Do this
http://www.honda-tech.com/showthread.php?t=1901557

 

Well, thanks, I count it again, it flashes 5 times. I am gonna get a scanner this week and confirm the code. I hope it just the map sensor ice up... it is pretty cold these week. And that explain why the car seems like running rich....