Okay so I've been dealing with this code for a while, I replaced the O2 sensor twice and the code keeps returning. What should I check/recheck?
P0139 keeps coming back
MADJEEP
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Check all grounds.
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4,653 Posts
which sensor did you replace? upstream or downstream?
which brand did you use?
need to check the following
A code P0139 may mean that one or more of the following has happened:
The oxygen sensor is faulty
The wiring to the sensor is broken / frayed T
here is an exhaust leak
Possible Solutions
The simplest thin
g to do is to reset the code and see if it comes back. If the code comes back, the problem is more than likely the rear driver's side oxygen sensor.
You will likely wind up replacing it but you should also consider these possible solutions:
Check and fix any exhaust leaks
Check for wiring problems (shorted, frayed wires)
Check the frequency and amplitude of the oxygen sensor (advanced)
Check for a deteriorating / contaminated oxygen sensor, replace if necessary Check for inlet air leaks
which brand did you use?
need to check the following
A code P0139 may mean that one or more of the following has happened:
The oxygen sensor is faulty
The wiring to the sensor is broken / frayed T
here is an exhaust leak
Possible Solutions
The simplest thin
g to do is to reset the code and see if it comes back. If the code comes back, the problem is more than likely the rear driver's side oxygen sensor.
You will likely wind up replacing it but you should also consider these possible solutions:
Check and fix any exhaust leaks
Check for wiring problems (shorted, frayed wires)
Check the frequency and amplitude of the oxygen sensor (advanced)
Check for a deteriorating / contaminated oxygen sensor, replace if necessary Check for inlet air leaks
My book says-code P0139 - bank one,sensor two.Since we're only dealing with a four cylinder,[one bank], that makes it easier as there are only two O2's used,the one closest to the motor[sensor 1] and the one furthest from the motor,[sensor 2]. So, according to the P0139,sensor two would be the problem and probably should be replaced.If it's original,or you've got quite a few miles on the vehicle,OR,the vehicle does a lot of shot hop driving [start it,drive it a few miles ,shut it off,and so forth,that would foul it up.And then sometimes,an O2 sensor will just go bad for no particular reason.Anyways,that's your starting point and more than likely,the problem.Good luck!!!
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what brand sensor did you use?
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I've read more than once that Bosch sensors are not liked by the Pat, I have to get a new O2 sensor myself (bank 1 sensor 2), which is after the Cat and the NGK sensor is $119 (Bosch is half that - and OEM is priced like it belongs on the MARS Rover)...wondering if the NGK is any good.
OEM sensor is $117
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12,339 Posts
If you have a 4x4, check the top of the maniverter for cracks.
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