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2009 Ford Focus P0136 O2 Sensor Error - Third Occurrence in 3 Months

Model: 2009 Ford Focus Fault Code: P0136 Posted: 2018-09-07 00:43

Hi everyone, I've been experiencing the P0136 diagnostic trouble code for the third time in the past three months. Each time, a local garage has replaced the oxygen (O2) sensor with a new Ford original part. Six months ago, they also replaced the upper O2 sensor due to another issue—though I'm not certain if it was P0133 or another code. Given that this problem persists despite repeated sensor replacements, what could be causing it? How can I properly diagnose and verify the root cause? Any insights or troubleshooting steps would be greatly appreciated. Best regards, Omer

Related fault codes
P0136
Comments (4)
Anonymous 2018-09-07 06:56

I recommend starting by graphing all O2 sensor voltage readings under various driving conditions using an OBD-II scanner app like Torque Pro, paired with an OBD adapter. Sharing these graphs will help identify potential issues or rule out faulty sensor behavior.

Anonymous 2018-09-10 06:12

With the ignition on, check for power at the O2 sensor connector—specifically look for a voltage reading of approximately 0.45V to ensure proper electrical connection and signal integrity.

Anonymous 2018-10-30 09:46

Hi all! I've uploaded O2 sensor data collected using the Torque app. You can view it here: https://files.fm/u/99fvg232 Any feedback or analysis would be very much appreciated. If additional information is needed, please let me know. Thanks, Omer

Anonymous 2018-10-30 20:46

The O2 sensor data shows brief 'bottoming out' events—both front and rear sensors momentarily dropping to low voltage values a few times. This could potentially occur during deceleration, though it's difficult to confirm without knowing the exact driving conditions when the P0136 code was set. Freeze frame data from when the code triggered would be helpful in identifying operating conditions. I recommend visiting my project site at pidfusion.net and comparing your vehicle’s behavior with known Ford 1.6L O2 sensor data logs. Be sure to use the blue buttons to view line graphs for clearer analysis.