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P0174 - System Too Lean Bank 2 Help

33K views 16 replies 4 participants last post by  jroddvette 
#1 ·
hey guys, i have a 2005 SE with 70k miles.
i'm getting a check engine light for P0174. does anyone have any suggestions on this problem?

i have cleaned the MAF sensor & throttle body with the appropriate cleaner, checked for vacuum leaks as best i can. i was thinking about swapping the O2 sensors from one side to the other to see if the code would change to a lean condition on bank 1 instead.
any other ideas before i buy a new MAF sensor?

thanks, Jared
 
#4 ·
how have you check for vacuum leaks? only bad ones will show with spraying and checking for a stumble. I always use a scanner that reads STFT, and LTFT(short and long term fuel trims.) if your LTFT are a high positive its adding fuel for a constant vacuum leak(or what it thinks is one due to a MAFS fault or 02. most often it is not a 02 but leak or MAFS. You need to erase the LTFT or it can mask a repair and make you think youve not fixed a issue because it will ALWAYS run under preconcieved faults that it will not correct before throwing codes or creating additional fault. DO this by doing a hard reset that clears all volatile memory from all modules. Disconnect battery negative cable and touch the disconnected neg cable to the positive. this discharges all capacitors on the truck/car and erases volatile memory(erasble memory like LTFT) It will be at "0" then. Now flip over to monitor bank 1 STFT and spray suspect areas again. When the STFT go into negative you found a vacuum leak(its puulling fuel from injectors because you induced fuel source through vacuum leak) This will let you see what the ECU sees through the 02 and is way more accurate than you spraying and trying to feel a stumble. IF there is no change then yes you can swap upstream 02's and see it the fault follows the 02. past that I too would replace the MAFS
 
#5 ·
jr, in my case the dealer originally said bad MAF, I replaced it. Couple days later codes came back, I had 0174 and 0172iirc. Raised hell when I went back, they actually did their job and found out it was the Air Fuel Meter Sensor. Most factory mechanics are quick to jump on MAF, because that is what they are taught to blame at the factory schools, and they will often not even bother to run proper diagnostics. Some that haven't drank the kool-aid will actually not just stop as soon as they see a K&N style filter.
 
#6 ·
so i swapped the front O2 sensors from one side to the other and now i'm getting P1281 & P0300 and it's running terrible.

the short term fuel trim 2 was at -25 at idle while the other side was 3.9.
so i think it looks like the front O2 sensor on the drivers side is the problem.
what do you guys think?
 
#10 · (Edited)
UPSTREAM AND DOWNSTREAM ARE DIFFERANT BUT YOU CAN SWAP SIDE TO SIDE, JUST NOT UP AND DOWN. LOOKS LIKE THE LAMBDA SENSOR IS FAULTY PULLING FUEL AT MAX AMOUNT. FOR DRIVERS SIDE WHICH IS THE P1281 A/F SENSOR CODE. BUT THAT STFT SHOWS A RICH CONDITION NOT LEAN. YOUDE HAVE TO LOOK AT THE READINGS AND VOLTAGES...HERES A FLOW CHART


http://library.alldatapro.com/allda...4853741/96340231/96340248/176614763/178112946
 
#11 ·
i just started getting the P1281 & P0300 after i swapped the two upstream sensors. no more P0174. so i just bought two new Bosch upstream O2 sensors and i'll put them in tonight and see what happens...

this thread on justanswer . com seems just like my problem.
he replaced the O2 on bank two and it didn't fix the problem even though that was the side that the code was for. once he replaced the bank 1 O2 the problem was fixed. http://www.justanswer.com/nissan/67mdv-original-condition-06-titan-p1281-a-f-sensor-bank-2.html


i think the sensor on my drives side(bank two) was bad hence the P0174 code.
then i swapped the two sensors and now i'm getting P1281 & P0300.

god i hope i'm right...

Brutal, thanks for the link! but it doesn't seem to open.
 
#12 ·
HMMM I GUESS IT ONLY RECOGNISES MY PC FOR PASSWORD ACCESS. I CAN COPY BUT IT LEAVES OUT PICS. GOD KNOW WE ALL LIKE PICS:)
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2005 Nissan-Datsun Truck Xterra 4WD V6-4.0L (VQ40)
Vehicle Level A L L Diagnostic Trouble Codes ( DTC ) Testing and Inspection P Code Charts P1281


P1281


DTC P1281 A/F SENSOR 1

Component Description






The air fuel ratio (A/F) sensor is a planar dual-cell limit current sensor. The sensor element of the air fuel ratio (A/F) sensor is the combination of a Nernst concentration cell (sensor cell) with an oxygenpump cell, which transports ions. It has a heater in the element.

The sensor is capable of precise measurement Lambda = 1, but also in the lean and rich range. Together with its control electronics, the sensor outputs a clear, continuous signal throughout a wide Lambda range (0.7 < Lambda < air).

The exhaust gas components diffuse through the diffusion gap at the electrode of the oxygen pump and Nernst concentration cell, where they are brought to thermodynamic balance.






An electronic circuit controls the pump current through the oxygenpump cell so that the composition of the exhaust gas in the diffusion gap remains constant at Lambda = 1. Therefore, the air fuel ratio (A/F) sensor is able to indicate air/fuel ratio by this pumping of current. In addition, a heater is integrated in the sensor to ensure the required operating temperature of 700 - 800 °C (1,292 - 1,472 °F) .






CONSULT-II Reference Value in Data Monitor Mode






On Board Diagnosis Logic

DTC Confirmation Procedure

NOTE: If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.

WITH CONSULT-II


Start engine and warm it up to normal operating temperature.
Select "A/F SEN1 (B1)" or "A/F SEN1 (B2)" in "DATA MONITOR" mode with CONSULT-II.







Check "A/F SEN1 (B1)" or "A/F SEN1 (B2)" indication. If the indication is constantly approx. 0 V , go to "Diagnostic Procedure". If the indication is not constantly approx. 0 V , go to next step.
Turn ignition switch OFF, wait at least 10 seconds and then restart engine.
Drive and accelerate vehicle to more than 40 km/h (25 MPH) within 20 seconds after restarting engine.







Maintain the given conditions for about 20 consecutive seconds . NOTE:
Keep the accelerator pedal as steady as possible during the cruising.
If this procedure is not completed within 1 minute after restarting engine at step 4, return to step 4.
If 1st trip DTC is displayed, go to "Diagnostic Procedure".
WITH GST
Follow the procedure "WITH CONSULT-II" above.
 
#14 · (Edited)
YES YOU DID, BUT get these and thatll fix the cel for 02's, they go in the downstream 02's. Ive used these on customer cars, theyre hi quality and work great. I dont have cats, I built a custom stainless exhasut from headers back and turned off cat codes forever with Uprev software
http://www.bigdaddiesgarage.com/?gclid=CNDO9bKVhrMCFUHNOgodD0UAYw
 
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