How to reset electronic control unit (ECU) for vauxhall vectra 1999-2000 year (V reg)?

My Vectra is 1795 cc petrol engine.The problem is.When I'm driving and take off my foot from gas pedal to change a gear by pressing clutch,the r.p.m does not drop down and I have to press gas again to drop running engine down.It's not always happen but sometimes.Another issue is.When engine running on low r.p.m about 800,such I'm stopped on street lights or waiting for something and do not turn off engine the motor try to stop and after come back,so r.p.m goes up and down and again and again.It's also not always but sometimes.Someone told me to reset ECU


Thank you|||You can reset it by taking the battery offf and leaving it off for a day. It is unlikely to cure the problem as the fault is almost certainly down to a worn out or dirty idle air control valve.|||Someone is being too technical concerning the control unit.


It will either work as it should or pack up altogether.





Far, far more likely is simply a frayed or sticking throttle cable.


This obviously runs from the throttle pedal to the carburettor, so it worth disconnecting both ends and having a peek to see if there is any prob.





One strand of the inner catching on the outer would explain all|||very common fault ecu reset wont cure your throttle body is gummed up with hardend oil due too bad crankcase vetilation you need too clean out the throttle body and breathers ensuring the rubber hoses havent prerished and collapsed in on themselves and get the breather mod kit from vauxhall they are cheap and easy diy fit








EDIT just remembered a faulty cam sensor causes a similar prob on these have a look at the wire for it they go brittle and crack have a look at this also|||It sounds to me like your throttle is sticking. Here's a little test you can do, when you take your foot off the gas, and your rpms don't drop, put your foot under the gas pedal and pull up on it. if the rpms go down, then your throttle is sticking open. You can buy some throttle body cleaner for it at any autoparts store and clean it out, it's extremely easy to do. I had this same problem.





Could also be a mass airflow sensor, or tps.(throttle position sensor)


But to reset your ecu, disconnect the ground cable from your battery for 15 seconds and then reconnect it.