Hi guys,

I have a problem wth my 4g93T which O2 sensor's wire was discontinuous (Putus). Now my engine become unstable rpm when idle.I guess stepper motor, but after changing it..this problem still happen but less than before.Does it come from discontinuous O2 sensor's wire?

yes... comes from disconnected O2 sensor wire... get it connected back or change new one...

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Change to new O2 sensor, if unable to get new sensor, join back the wire.
Reset ecu after u change / join back the wire.

Ok bro, i will try it and will comeback wth the outcomes later

Bro, my mechanic just connected that disconected O2 wire. But i dun see whether he reset the ECU or not, he never touch anything just disconet & reconet the +ve baterry wire after finished it. Now, the problem still going on. Normally, what's the best practice to reset the ECU?

Disconnect -ve battery wire for 5min then connect back.
If budget allow, look for new O2 sensor as rejoin wire might affected accuracy in voltage feedback.