2005 Mazda3 2.3l engine stumbled just after a cold start and threw a P2188. I picked up an OBD reader and notice the values/graph of the front O2 sensor looks like a heart attack going from .8 to .08 but the rear sensor has a much smoother operation, follows throttle, etc. I replaced the front sensor and the new one puts out the same looking graph. Can anyone tell me if their front sensor has the same eratic values or should both sensors have more similar values. Thanks
