hi folks i have a 1999 civic 4 door
i just replaced the cat
then the lamba sensor
{ now the cat light is on { { and when i start it up it reve to 1500 for a bit then goes back to 1000, until i start driving then its at a constant 1500 revs
any help would be great
thanks

 

Does the engine warm up? it will normally idle fast when cold. Could also be a problem with the coolant temperature sensor (screwed into the head underneath the distributor, with two wires, make sure it is plugged in). Since the CEL is on, pull the codes. Check that the throttle cable goes slack and the throttle closes fully. Check the vacuum hoses, any air leaking into the intake will increase idle speed. Clean the IACV. If the idle is out of control for whatever reason you get an "IACV" code though that may not necessarily be the problem.

 

thanks for reply
i will try all you said and let you know
thanks
john

 

As mk mentioned, pull the CEL codes (click link in my signature) and look for a disconnected vacuum line.