P0138 Mazda - CEL goes off afternoon!!!

Question

Hi,
Can anyone give a right solution? I have a 2007 Mazda 3 Sedan (2 liter). Recently CEL light comes on but the car runs well. It comes on after 1-2 minute of start up and after frequent stops (I am a sales reprehensive ) the light will goes off at the middle of the day...!!! Is that the problem of the sensor or something else?? I got the code as PO 138..Every one ask me to change the sensor....But If the sensor itself is the problem then how there is no CEL afternoon?? Plz help me...

Answer 1

P0138 H02S sensor circuit high voltage Bank 1 Sensor 2

Bad connection of the rear 02 sensor can set  this,One of the jobs for the ECM is to look for open circuit, short circuits, and grounded circuit, These condition will set the CK ENG LT on right away, because what you have is  a intermittent condtion the CK ENG LT can turn off but will remain in the pending codes .