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So, getting these codes on GF's 2008 G35, 112K miles. P0138 is O2 voltage high on B1 S2 and P0037 is O2 heater low on B1 S2. So far have done the following:
1. Replaced cat, pass side;
2. Replaced O2, B1 S2;
3. Replaced first cheap O2, B1 S2 with DENSO 234-4380;
4. Did A/F relearn procedure by unplugging MAF (both sides while warm) and clearing codes.
5. Checked the O2 fuse (Pain in the A, located on pass side of battery box; Google how to get to this fuse box, if you need to do this).
6. Have searched here and elsewhere to see what else I may be missing.
I'll add, also got P0158 (O2, B2 S2- which tells me B2 S2 is weak) a couple of times but, B1 S2 comes back every time after about 10 minutes driving. SES/MIL lights after about an hour or so. Monitoring systems all PASS after extended driving, except Catalysis??? I'm using a generic OBDII scanner (Easy OBDII) and get inconsistent O2 voltage readings. B2 seems okay; settling around 0.3V with fuel mixture flipping from rich to lean. But, B1 is always rich and voltage some times looks okay but most of the time it's stuck at 1.275V!
Anyway, need some help here.... I'm thinking bad wiring. Can anyone tell me how to check the voltage at the female end (from the main harness) of the O2 wiring harness with the ignition ON? I've searched and am not sure what I'm supposed to see... The O2 B1 S2, 1.275V on the scanner, (with sometimes normal .2 to .9V), makes me think there's a short or open current to the O2 that is intermittent... And, is this a common problem and where should I look for fubarred wiring?
BTW, I'm a former Q45 and 240Z owner and love the GF's G35. It runs like a bat out of hell, and we'd hate to get rid of it. Don't have much reason to post here, as my cars are European V-8 and V-12. But, I'll be sure to post my results, with pics, if I can figure this out...
Any help or comments are greatly appreciated.... Regards... Mark
Here is a link to the FSM, look under section EC - Engine Controls, in the table of contents find your DTC # and go to that section for steps on troubleshooting the wiring.
If voltage is stuck at 1.275 and won't fluctuate I'm guessing it's a bad sensor, where are you buying them from?
If BOTH BANKS are having issues like that though then I would start looking for vacuum leaks.
There's also the option of paying for a 1 hour diagnostic from Nissan after you have exhausted all other options.
Yes, I've replaced the Right, Passenger side cat and downstream O2. BTW, we were also getting P0420 before replacing the cat and that code has gone away. The first O2 was a generic on Ebay and, IIRC, it gave the 1.275V. Replaced with a Denso (about 5 times the cost) and it to often gives 1.275V, but not always. Sometimes it gives appropriate voltage on the scanner (0.9- 0.2V) and at other times it's stuck at 1.275V.... Makes me think it's bad harness... But, I'm using cheap (free) EasyOBDII software and ELM327 so, I haven't been real certain of the accuracy of the O2 voltage reading... it only has two O2 voltage readings that show up.
Also, the P0158 (left bank code) has only shown a couple of times and the O2 voltage for that bank seems reasonable. Although, I think that O2 needs replacement... just not as obvious as the bank 1. So, for the time being, I've ruled out vacuum leak. Car runs really smooth and quite. And, you can barely tell it's running when standing in front of it! So, for now, I'm not thinking vacuum or exhaust manifold leaks???
And thanks for the e-manual link. I had found that but didn't know what the section codes meant. I think I get it now. Slideshare.net has the Quick Reference Index on the first page at :
The EC alone has 606 pages, so that will give me something to look at. I was wondering if someone knew off-the-top-of-their-head what readings I should get on the 4 slots on the female side of the O2 connection. I'm still thinking wiring??? I only get to check on the girlfriend's car a few hours a week-- it's her daily driver, so it may be a while until I get it back up on jack stands....
The FSM starts with the .FWD document, the EC -Engine Controls has a comprehensive table of contents to help you quickly get to the correct page. Basically you just pick the trouble code from the list and it sends you to that section.
I got it. fwd.pdf is the last file when I open https://www.nicoclub.com/archives/in...e-manuals.html. First is ACC.pdf - Accelerator Control System. All the sections are in CAP's, except fwd.pdf for the 2008 G35, which may be why it's at the end (...I figured the Quick Reference Index was in there, just didn't know where. Hence, I had to refer to slideshare.net to find the Index, which has the index on the first page.) Sorry, as you said, it's not that complicated... For those like me, doing this for the first time, Cleric's link has a list of about 50 pdf files that comprise the factory service manual (FSM)... They're broken down by category, such as EC for Engine Control Systems. The entire FSM makes "War and Peace" look like bathroom-break reading!!!
And, back to GF's car-- which I don't have right now to diagnose -- the FSM got me this far:
F54 is the connector for O2, B1 S2 and I now know how pins 1-4 are oriented. It also tells me that F54 is at the end of the engine compartment "F" harness:
Since everything else seems to be working okay and we don't have a blown O2 fuse, the problem probably lies with the connection or at least a short portion of the engine compartment "F" harness.
The FSM says to check continuity (zero ohm reading) for some of the pins on F54, between F54 and the ECU. That's a pain! That connection, F54, is under the car and probably prone to damage. Unfortunately, I won't be able to crawl under there to inspect it for a while. GF has the car...
Also, the FSM says the O2 heater will active-- and trigger a P0037 code-- when warm and reved to 3.5-4K rpm for 1 minute and idle for 1 minute. Then it says:
So does that mean terminal 2 should be battery voltage (12-13V)? Sorry, I'm probably stating the obvious... I don't see anything about terminals 1,3 and 4??? IOW's is terminal 2 the battery voltage that powers the O2 heater??? But only after triggering it with high rev's followed by idle???
Again, sorry for all the questions. I just don't have much time to diagnose and wanted to know what I'm looking for in the time allotted....
fwd.pdf is at the end of the 2008 factory service manual (FSM).... Maybe because all the files are in CAP's, except fwd.pdf. As you said, it's not complicated but a little confusing for first-time users, like me. But, very useful...
Here's what I've gleaned so far:
So, the F54 connection is under the car and at the end of the Engine Compartment Harness. If I'm reading this right, you can trigger the 12V input at terminal 2 of F54 by revving a warm engine to 3.5-4K rpm for 1 minute and 1 minute of idle. That will set P0037 and then you can check if terminal 2 is at 12V.
Since F54 is at the end of the engine compartment harness and under the car, it's probably prone to damage. And, since we're not getting other problems, the problem, if wiring, should be at the end of the harness and hopefully easy to find.
Unfortunately, I don't have the car here and can't check my theories for a while.
Again, your help in helping me learn how to access the FSM had been a great help. What I can't find is what I should see on pins 1,3 and 4 on the F54 connection with a voltmeter. FSM just says, check fuse-- which I did-- and check continuity (zero ohms) between F54 and ECU-- a big pain...
No worries, there will also be line diagrams for each circuit that have pin numbers on them. For example, if you use the table of contents in section EC - Engine Controls and it refers you to harness then you can go to section PG - Power and Grounding to see the actual circuit.
You already found harness F54 for the O2 sensor and yes it's saying that pin 2 will have battery voltage. Underneath the column for "ground" it might tell you an actual point to test, when it simply says GROUND you can test against any point of the chassis. So using your multimeter on GROUND and terminal 2 the expected voltage is BATTERY VOLTAGE.
Lots of stuff runs at 5v on these vehicle though so be sure to check that column to see what's expected.
Harness F101 for the ECM is located in PG - 13. Don't confuse F101 and F102, F101 is the wiring harness, F102 is the ECM itself, but they are both listed as "ECM" in that section.
All I need now is the car and the time to start troubleshooting! However, if anyone knows what voltage, if any, pins 1,3 and 4 should have, that is far easier to check than the suggested continuity (zero ohm) tests between the F54 and F101 connection....
