I need to replace an O2 sensor. The trouble code is P0154 "Oxygen sensor circuit - No activity detected (bank 2 sensor 1). Which of theses 4 possible sensors does this code refer to?1. Upstream sensor ( front cylinder head)2. Downstream sensor (front cylinder head)3. Upstream Sensor (rear cylinder head)4. Downstream Sensor (rear cylinder head)Thanks much for any information you can provide!


Asked by May 13, 2013 at 08:51 AM about the 2002 Kia Optima SE V6

Question type: Maintenance & Repair

5 Answers


I believe its choice #1.

1 out of 1 people think this is helpful.

The motor sits sideways kos.

1 out of 1 people think this is helpful.

I believe its choice #1. It's definitely not #2 or #4 - They are technically called catalyst monitors. --- The passenger side bank on a forward facing engine, or the bank closest to the firewall on a transverse mounted engine, is bank number 1, so the forward / upstream sensor on that bank would be "bank 1, sensor 1." --- The driver's side bank (forward facing mount engine), or front bank (transverse engine) would be bank number 2, thus the forward / upstream sensor on that bank would be "bank 2, sensor 1," and the rearmost / downstream sensor on that bank would be "bank 2, sensor 2."

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Best Answer
Kos MotorCars

It is the "Left Front"


kos the motor sits sideways as I already tried to explain. yes it is the left front sensor but the person is asking which one that is, and from the list of choices he has. "left front" is not an option. he wants to know if its on the front manifold or the rear since the since the motor sits sideways in the vehicle.

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