2001 Nissan Maxima service engine soon stays on code from autozone scanner PO139 and PO138. What do these mean? Was told could be oxygen sensors could be bad and there are two of them on this car.Or fuel injector is leaking or needs to be cleaned? What would be my best next step to take to solve service engine light staying lit.
Code p 0138 refers to 2 items
1--heated oxygen sensor(HO2S) 2 bank 1--high voltage ==causes --wiring short to positive --HO2S---ECM
2--oxygen sensor (O2S) 2 bank 1--high voltage ===causes wiring short to positive ---ECM
code p 0139 refers to 2 items
1--- heated oxygen sensor (HO2S) 2 bank 1--slow response ===causes --heating inoperative --wiring--ECM
2--oxygen sensor (o2S) 2 bank 1 slow response ===causes --wiring --- O2S
heated oxygen sensors9HO2S) are in the exhaust manifold before the cat converter
Oxygen sensors (O2S) are after the cat converter
it is indicated that the HO2S is faulty-
check the wiring and /or replace both sensors
SOURCE: knock sensor
For replace the knock sensor on a maxima.
You need to remove the intake manifold.
If not, you have no access to the sensor.
This prosses require about 3.5 hour labor.
SOURCE: Check Engine Light 1996 Nissan Maxima
The best way is to use a scan tool to clear the codes, that will turn off the light, also disconnecting the battery over night may work, but no completely sure about that, it varies from year to year.
SOURCE: 2002 maxima check engine light came on
First thing I would do is make sure you battery cables have a flawless connection. I had a Honda with a similar problem. I changed the battery cable and it all went away. Like magic. Sometimes these can be a simple fix.
SOURCE: check engine light stays on, need to know where oxygen sensor is
If you have an autozone or advanced auto near you take it there,they don't charge to put a scanner on it.
SOURCE: 1996 Nissan Maxima oxygen sensor
hye there ,,there are 3 o2 sensors on your car,,one for each bank,,,and the 3rd sensor is located after the cat this one usually goes first,,,,just make sure you no if your cars an import or not as they can be different,,,then you should be safe when ordering ,,hope that helps,,,
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Thank you Jimmmyi for your answer to my question on codes PO139 and PO138 which you say are related to bank 2 oxygen sensors. Are these two oxygen sensors only accessible by jacking up the car and putting the car on jack stands? Are they easy to replace if I was to do it myself.
Not sure on exact position of sensors, try follow exhaust up from cat converter to locate the sensors, you may have to jack vehicle.If located it is a job that is easy enough to do just a matter of unscrewing and unplugging and screwing in correct new sensors.
Both Codes relate to bank 2 which are more then likely picked up from the oxygens sensors, still can be caused by injectors, exhuast leaks, remove the oxygen sensors before the cat converter and replace.
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