So i have a 98 honda civic 1.6L ex. The check engine light is on. Tried a code reader and it says its not connected to anything. Checked every fuse on the car and all are fine. The car also idols jumpy and revs high at stopped position. Figured the jumpy rpms was from me taking off cruise control and a poor vacuum leak but all vacuum lines are sealed. Anybody have any other ideas?

 

sticky throttle cable
dirty throttle body and sensors
bad Throttle Position Sensor

is the CEL (Check Engine Light) on?

 

Check engine light is on. Throttle cable seems ok and i cleaned the throttle body. Guess i need to look at the sensors next. Any idea on why the diagnostic reader when plugged in would say the device isn't plugged in to anything?

 

Try pulling the code by jumping the service connector above the ECU behind the front passenger kick panel. Click CEL link in my signature.

 

Thanks, i jumped the ecu and got code 67 which is my cat converter. Just replaced so now i need to figure out if that means sensor or the cat itself. Thanks for the jumping tip.

 

Code 67 is almost always caused by a bad cat. The only other fault that will throw code 67 is an exhaust system leak.

Make sure that you reset the ECU to make sure code 67 repeats. No need to chase non-repeating CEL codes.

 

can the o2 sensor short out and not be any good? also why would i not be able to connect a code reader to the normal ecu connection hub?

 

guess i'll check all my exhaust gaskets and connections to see if there are any leaks

 

thanks for the help

 

If only code 67 is thrown, then the secondary O2 sensor should not be considered.

Regarding the code reader problem, this is likely a separate issue possibly due to a bad code reader, bad wire in the DLC circuit, or even a bad ECU. You first may want to recheck the DLC fuse under the hood, however.