HELP: Engine check light issue(O2 sensor)
 

Problem: Engine check light : O2 Sensor error code only( went to a few workshop to check all say only 02 sensor error code.


symptom:


As per o2 sensor issue, notice drop in FC, but still not that bad, able to still do ard 450-500 per full tank.


However apart from the drop in FC, notice a few other buggy symptom.




1. Gear can't change smoothly, long rev between 1 to 2 and 3 to 4 gear. sometime only after I hit 80km/h then it up shift from 3 to 4 gear.


Also on slow drive, normally in gear 2 or 3. sometime there is sudden loud knock on the left rear end of the car which might result in car jerking also.


2. When engaging reverse, sometime it is very violent, the car will jerk when engaging the reverse.




Findings:
the Gear issues seem to subside if I warm up the engine before I drive off, at least for 2-3min.


Or if the gear change is not smooth, Cutting the engine and start again, will also get rid of the problem.


For both the above, not always successful but most time it work.






Help:


1.Can anyone advise if all the above issue is related to the O2 sensor, n will changing it solve all of the problem?




2. if it is not only o2 sensor issue, what other possible problem I m looking at


3. What e est cost to repair o2 sensor or what ever other problem


4. any recommended workshop.






THanks!

Forget to add: mine mazda 3 sport 1.6 2006 ride.