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Discussion Starter · #1 ·
My 2015 MKC Select has been throwing a P0137 code at random times for the last 3 years. It happens on cool/cold damp/rainy days when I take a short trip or a slow through town trip or sit idling.

The books says "P0137 Code: Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2)". This is caused when the O2 sensor beyond the catalytic converter does not create the expected voltage withing the required time (5 minutes). Causes:
Vacuum leak
Exhaust leak
Bad catalytic converter
Bad B1S2 O2 sensor.

I have had the car checked for vacuum and exhaust leaks (dealer and I also did 2 with my own smoke pump) - no leaks.
Both O2 sensors and the catalytic converter have been replaced.
The wiring and connectors have been visually checked and I did a continuity test with ohm meter.
Voltage coming out of O2 sensor checked - okay.

The dealer says the only thing left to do is replace the ECM/computer.

Is there a way to hack the system to extend the time before the system sees a fault?
 

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Did you check the heater circuit?
 

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Yes it is, it's usually the two gray wires but it's whatever two are the same color, if you don't have good power to the heater, it'll take longer than 5 minutes to warm the sensor up and then you'll end up with some incorrect readings. In your initial post, you said you checked the voltage coming out of the sensor, did you mean the voltage produced by the sensor or the voltage to the heater
 

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Discussion Starter · #5 ·
I'm not sure - that was done by the dealer. I will have to see if there is a procedure online.
I did a continuity test from O2 to the plug to make sure the wires weren't broken/cut/chewed.
 
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