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Question

Can't find right O2 sensor on Maxima


Sent to Car Experts September 13, 2005 11:35 p.m.
check eng. light on for a long time on 2001 Maxima... need to fix so i can pass inspection, car runs fine...Autozone ran scan which shows codes P0140 and P0158&P0159 which are for O2 sensors... my problem is i don't know which ones these scan numbers refer to....the maxima has 4 sensors and i have located them on the car....Autozone identifies them as follows: P0140 being Bank 1, sensor 2 & P0158 & 159 being Bank 2, sensor 2....a diagram i rec'd from a Nissan dealer parts person uses DIFFERENT terminology to label the O2 sensors...in addition, note that the O2 sensors on the car have different colored wires - blue, red, white and black....Nissan terminology is Bank 1, sensor 1, front (black); Bank 1, sensor 1, rear (white); Bank 2, sensor 2, front (blue); Bank 2, sensor 2, rear (red)...i think the most useful answer would be to tell me which Autozone code refers to what sensor on the car by wire color
Customer (name blocked for privacy)
Status: Closed   Value: $8   
Answer
September 14, 2005 5:25 a.m. (5 hours and 49 minutes later) 		REPLIED Check Mark

Those are both downstream sensors. that means they are the ones AFTER the catalytic converter for both sides.

Bank 1 is the rear bank toward the firewall and bank 2 is the front..



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PictureHammer Time  -- L1 Master Technician -- 98% Positive Feedback on 2710 Car Accepts
ASE Mastertech with Adv level Engine performance cert.
Reply to Hammer Time
Sent September 14, 2005 10:44 p.m. (17 hours and 18 minutes later)
hi...your answer doesn't really help me pinpoint which sensors i need to replace which is why i was hoping to go by wire colors....i can't tell upstream from downstream and i'm not sure what you mean by "sides"....the 4 sensors run more from front of car toward firewall....one just behind the radiator in i believe the manifold, if follow pipe down underneath car come to second one located on top of pipe, a little further back one inserts into front of what i believe is a cat, and fourth one is further back in hard to reach spot closest to firewall...are you specifically familiar with the maxima sensors
Customer (name blocked for privacy)
Answer
September 14, 2005 10:52 p.m. (8 minutes and 0 seconds later) 		REPLIED Check Mark
The engine has a left bank and a right bank. since the engine is mounted sideways, that ends up being front and rear. Each side of the engine has a sensor in the exhaust pipe leaving that side of the engine before reaching the catalytic converter. Those are considered upstream sensors. Another set of sensors are either in the converter or after it. Their exclusive purpose is to monitor the catalytic converter.they are called "downstream" sensors and those are the ones setting the codes on your car.

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PictureHammer Time  -- L1 Master Technician -- 98% Positive Feedback on 2710 Car Accepts
ASE Mastertech with Adv level Engine performance cert.
Reply to Hammer Time
Sent September 15, 2005 11:22 a.m. (12 hours and 30 minutes later)
finally an explanation that makes some sense to me...i thought references to a side were to a side of the car like drivers or passengers side...the maxima diagram i have now seems more logical....one other thing & then i will accept your answer...after the sensors are installed and i start up the car will the check engine light be out? will it take a while? if so how long? does anything like the "computer" need to be reset?
Customer (name blocked for privacy)
Answer
September 15, 2005 1:10 p.m. (1 hour and 47 minutes later) 		ACCEPTED Check Mark
Different cars respond different ways as far as displaying the light and clearing the codes. If it does stay on, just stop by AutoZone and they will clear them for you.

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PictureHammer Time  -- L1 Master Technician -- 98% Positive Feedback on 2710 Car Accepts
ASE Mastertech with Adv level Engine performance cert.

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