P1273 Nissan Code - Air Fuel Ratio Sensor 1 Bank 1 Lean Shift Monitoring

Any possibility that this code is caused by a dirty/blocked air filter?

Yes, it is possible. If the filter is dirty, start by replacing the the filter and clearing the code.

Hey, is this code possible after changing gas. I went from 87 to 89 and the check engine soon light came on.

Yes, it is possible.

what needs to be done to correct this code problem?

is the A/F sensor 1 the same as the O2 sensor 1 (oxygen sensor)

More than likely you need to replaced the sensor to correct the problem and if possible reprogram the ECM (Engine Control Module) as well.

In a one word, yes.

With the code p1273 showing on the diagnostic meter we checked the output from the pressure control valve which showed a fluttering current indicating that this part is the problem.

If p1273 is a lean-condition code, how could it be a dirty air filter?  This would restrict airflow and make it run rich, not lean . .

Not for restriction, but for dirt on the air filter that can go on the MAF.

 So if the filter's dirty, then cleaning the MAF with MAF cleaner should be done at the same time, no? (Esp. if replacing the filter doesn't do the trick.)

Could the air flow code come on if the secondary cat was hollowed out the bank 2 02 sensor is before the cat so is it useless being there? Or does the sensor read the back pressure and use all the excess fuel

When I test the injectors what are the ohms supposed to be

What model and year is your Nissan?

i have nessan quet 2005 code 1273

You probably have to replaced the the "Air Fuel Ratio Sensor Bank 1: to fix the problem.

Location of the sensor: http://nissanhelp.com/diy/q...

I have a leak in my flex pipe. Is this causing me a P1273 code?

Yes, it's more than likely that is the cause of the problem

I have replaced the sensor which was causing the check engine light to be on and turned it off, but it came out again after two days and they told me that the first 02 sensor at the same side needs to be replaced because the new one makes the old one look bad? is this true ? please I need a help as soon as possible ( my car: 350z 04')

I had this same problem over and over . . my 350 had an ECU tune for
CAI, P&P throttle body, intake plenum spacer,
conventional-substrate high-flow-cat's and some other stuff too . . but
when I put on Berk high flow cat's with metallic substrate, they flowed so much better, that it
started throwing these same codes and shop after shop couldn't really
say what it was other than what my own logical conclusion came to which
is that the Berk's flow so much better (as witnessed by both performance
as well as sound) that they are causing the front sensors (in the
exhaust manifolds) to read "lean" because they are allowing so much more
air to flow through, and then the ECU reads this lean condition and
throws the codes but then compensates by putting more fuel into the
mixture to balance it all out . .

So yes, the code reads "lean" and turns on the light . . but then the
ECU compensates. Bottom line: The ECU is temporarily "fixing" the
problem for you but you need to address the core issue which is either
a) an intake leak; found out my CAI had a leak AFTER the MAF, and then
fixed it . . . in my case it was a slight leak where the CAI intake
tube connected to the Throttle Body so small that it took a pressurized
smoke-test by Uprev to find it . .

or b) an exhaust gasket leak between the exhaust manifolds and the cat's (High-flow cat's in my case). Found that too . .

All that said, I fixed the intake leak (or actually Uprev did), then
fixed the exhaust gasket leaks (new OEM gaskets), and yet the LIGHT
still came on even though the leaks were ALL TAKEN CARE OF. Why?
Because - as Uprev suggested - the Berk HFC's are allowing enough MORE
airflow through the engine than my TUNE was allotted for .. I know this
all to be true now because after going through all the above, my gas
mileage went down several mpg's until I fixed the intake and exhaust
leaks . . after which, the mileage went RIGHT back up to normal (very
good; 21 city, 26+ hwy). The light's still on though, letting me know
"Hey, you still need to get your car re-tuned after adding mod's that
significantly improve the airflow to a point that's outside the scope of
the factory programming" (or in my case, outside the originally
aftermarket programming by Technosquare in CA).

Okay. so i have a nissan maxima se 3.5. we had a lifter knock, took it in to get repairs made. the next day code p1273 came up. we had the bank 1 o2 sensor repaired. had to have nissan dealer do a self learning code clear on it. went 2 days check engine light came back. code p1273. now my understanding is 1273 is for bank 1 p1274 is for bank 2. im at a loss. we have had muultiple people look at it and the answers are not the same.1 says air leak in manifold, another says replace the catylists. yes all 3. another syas it might be an injector. please give me an idea that doesnt involve rebuilding the whole engine.

Since the problem started after the lifter replaced, the problem is more than likely an air leak. I suggest taking the vehicle back to the shop that did the lifter knock repair.

I have a 2005 Xterra, what is the voltages supposed to be on the bank 1 and bank 2 a/f sensors? I'm throwing a p1273 and p0430 at the same time. bank 1 reads .6 and bank 2 reads .28

At idle and engine warm up you should get the following values: (ground and wire color)

05 Altima with P1273 code. Replaced both O2 sensors, cat, and MAF sensor. No luck. Now what?

Did you clear the self learning? The light will not erase if you don't clear the self learning. Instructions here: http://nissanhelp.com/diy/a...
If the problem persist you probably have an intake leak.

05 altima fixed all the normal ... cat and manifold both o2 sensos and every 125 miles the ses light on comes on ......what now!

Did you performed the "Self-Learning Procedure" ? if you didn't, the the light will come back. There is a factory service bulletin for that problem.

Instruction to performed the "Self-Learning Procedure" here: http://nissanhelp.com/diy/a...

how

Can you please help I need to know where to locate the 2009 Nissan 3.0 TDi LDV air to fuel ratio sensor 1? I am a lady but I know you great guys out there will be able to assist. If possible pictures will be helpful. You can also send it to me via whatsapp 0725314050 or alternatively email to me at amanda@barrys-auto.co.za. I thank you in advance

I have an 04 sentra 1.8. I got a different o2 sensor code. I replaced the upstream o2 sensor and got the p1273 code. The MAF relearn worked for me after that (unplug the maf sensor, run the car, reset codes, idle for 10 min.) The car even runs better.

Note: I reset the codes by leaving the battery disconnected overnight with the two ends touching

Thank you for the information!!

Did you get at p0420 at first?

Sorry to say I think it was p1148.

I forgot to come back and add that my p1273 came back a month or so ago at the same time as an exhaust leak popped up just before the flex pipe.

Fixed the leak, cleared the code, all good again.

I DID have to do the relearn again. Seems like anything doing with exhaust requires it.

Could this potentially be caused by dirty injectors ? I have the code, but my car also hard starts, sometimes cranking a bit before it finally turns over.

Yes, dirty fuel injector could trigger the P1273 code. Also, make sure you are using high octane gas and if possible clean the MAF sensor.

Hey guys,
I had a P0420 code for several years and the P1273 for months.
At the time, and with my lack of knowledge, I didn’t care about the P0420 code …I thought it was only emissions. The code IS for emissions, but it can ALSO mean other problems exist too! I’ll explain later.
So I drove it like that for maybe 35k miles, maybe 40k.
A surprise pregnancy (no. 5) sent us over the baby seat limit for our larger ride. Lol
Alas, we had to buy a new car …and sell my faithful Altima (now at 201,000). This made the P0420 code more of a deal breaker. I wouldn’t get as much with the engine light on.
And so began my journey to a CEL-free dash!
I started with Bluedriver. So glad I did!! I was able to see my fuel trims!!!! Life changing tool!!!
I was at 9% on my long term and 17% on my short term!! This meant I had a few leaks!
I was opened up to the world of not trusting CEL lights! Curse you Bluedriver!! Lol
I started with a starting-fluid-spray-test and found the first leak. Turns out when I had replaced my PCV valve, I had dropped a small ring gasket that sat in the PCV-hose-to-intake port. Fixed that and watched the STFT drop to 14%. Still not good enough. Read that a lot of Altimas have cracks in their exhaust header. Checked that and found TONS! TONS! There’s my problem!
Fortunately, the cracks and the P0420 code are the same part. My destiny was calling me! I had to replace the catalytic manifold to WIN! Lol
.
So I first tried a $100 aftermarket catalytic converter/exhaust manifold on Amazon. Didn’t even come close to fitting! Should have known.
Returned that and bought a $350 “OEM” one from O’Reilly’s. That didn’t fit too well either. Ugh!
Engine side heat shield didn’t fit, so I left that out. Had to modify a few heat shield holes for the radiator side.
Had to use spacers and different bolts to match the manifold mounting bracket up near the bottom. Finally got it in. What a pain!
Also found out that my exhaust pipe bracket had been squashed from coming down off a curb from our yard or something. So I replaced that and it helped the pipe meet up with the new manifold even more. Still wasn’t OEM though as O’Reilly said it was. Pshshh.
Anyways, so I started the car up.
P0420 gone! Boom. Within the first drive cycle! LTFT went down to 0%! So awesome! STFT went to 9%. Nice!
.
Here’s where the crap hit the fan!
The dreaded P1273 started popping up to say hi. Ugh!
Went through a few fuel trim clearing procedures (including unplugging the battery overnight) and it just kept popping back up.
Tons of sites were saying it was a lean issue. Injectors, bad sensors, yada yada.
Tried replacing my sensors a few times. Both upstream and downstream! Nope. It came back.
.
Found on YouTube that ONE mechanic was saying this code also popped up from an EXHAUST LEAK after the flex hose joint. I had remembered that after I installed the new converter manifold that the flex joint just didn’t feel as nice of a fit when I had put it back together. It was tight, but just didn’t feel right.
So I looked at that while the car was running and sure enough, noticed that I could hear the engine when I put my ear up to the flex joint. There was a smaaaall gap where O2 could get in and throw the readings at the 2nd sensor! Not enough to notice a huge difference on my Bluedriver (2nd sensor was showing 0.265 volts), but enough to supposedly throw my P1273 code.
So I installed a few rings around the male pipe connector on the manifold to help lift the curved side of the flex pipe gasket out a little further to fill up that gap I was talking about. After a few rings that I had cut out of a tin sheet I was able to make it mesh good to work with the new manifold and old flex joint and pipe. Bolted it back up. Started the car. No more noise.
The car sounded better than it had in a long time! No cracks in the exhaust, no flex pipe leak!
Performed the fuel trim history clearing procedure.
Man oh man I can’t tell you how pleased I am!!!! LTFT is 0%! STFT moves around from 0 to 6%!
Been driving the car now for a long time and no codes!!! No P0420, no P1273!
Engine purrs!

Here’s my final readings:
(range includes cold start to warm engine, at idle and 3000 RPM)
STFT 0 to 6%
LTFT 0%
O2B1 0.12 to 0.9V
O2B2 0.28 to 0.31V
So what did I learn? Here’s the main things that will change my mechanic life forever:
1. Catalytic converters should last for 200,000+ miles with a well maintained engine. If you’re cat goes bad, you probably have other problems that just haven’t thrown a code yet.
2. You can have small problems with no CELs that can turn into big ones!
3. Fuel trims can really help diagnose issues!
4. The 2nd O2 sensor is not JUST used for exhaust emissions! The ECM uses BOTH O2 sensors to determine fuel trims (and lean or rich fuel conditions).

So what did this mean for me? That I will fix catalytic converter problems much sooner from now on if I plan to keep my car around past 200,000 miles.
If your engine is running rich for a long time it can damage other parts, and eventually expensive ones. I’ll admit, emissions aren’t my biggest concern. But I do care about engine longevity.
All that said, if you have a P0420, P1273, or P1274, hopefully my story will help save you some hassle.
Take care,
Benny

Hey guys,
I had a P0420 code for several years.
At the time, and with my lack of knowledge, I didn’t care about the P0420 code …I thought it was only emissions. The code IS for emissions, but it can ALSO mean other problems exist too! I’ll explain later.
So I drove it like that for maybe 35k miles, maybe 40k.
A surprise pregnancy (no. 5) sent us over the baby seat limit for our larger ride. Lol
Alas, we had to buy a new car …and sell my faithful Altima (now at 201,000). This made the P0420 code more of a deal breaker. I wouldn’t get as much with the engine light on.
And so began my journey to a CEL-free dash!
I started with Bluedriver. So glad I did!! I was able to see my fuel trims!!!! Life changing tool!!!
I was at 9% on my long trim and 17% on my short trim!! This meant I had a few leaks!
I was opened up to the world of not trusting CEL lights! Curse you Bluedriver!! Lol
I started with a starting-fluid-spray-test and found the first leak. Turns out when I had replaced my PCV valve, I had dropped a small ring gasket that sat in the PCV-hose-to-intake port. Fixed that and watched the STFT drop to 14%. Still not good enough. Read that a lot of Altimas have cracks in their exhaust header. Checked that and found TONS! TONS! There’s my problem!
Fortunately, the cracks and the P0420 code are the same part. My destiny was calling me! I had to replace the catalytic manifold to WIN! Lol
.
So I first tried a $100 aftermarket catalytic converter/exhaust manifold on Amazon. Didn’t even come close to fitting! Should have known.
Returned that and bought a $350 “OEM” one from O’Reilly’s. That didn’t fit too well either. Ugh!
Engine side heat shield didn’t fit, so I left that out. Had to modify a few heat shield holes for the radiator side.
Had to use spacers and different bolts to match the manifold mounting bracket up near the bottom. Finally got it in. What a pain!
Also found out that my exhaust pipe bracket had been squashed from coming down off a curb from our yard or something. So I replaced that and it helped the pipe meet up with the new manifold even more. Still wasn’t OEM though as O’Reilly said it was. Pshshh.
Anyways, so I started the car up.
P0420 gone! Boom. Within the first drive cycle! LTFT went down to 8%! So awesome! LTFT + STFT went to 9%. Nice!
.
Here’s where the crap hit the fan!
The dreaded P1273 started popping up to say hi. Ugh!
Went through a few fuel trim clearing procedures (including unplugging the battery overnight) and it just kept popping back up.
Tons of sites were saying it was a lean issue. Injectors, bad sensors, yada yada.
Tried replacing my sensors a few times. Both upstream and downstream! Nope. It came back.
.
Found on YouTube that ONE mechanic was saying this code also popped up from an EXHAUST LEAK after the flex hose joint. I had remembered that after I installed the new converter manifold that the flex joint just didn’t feel as nice of a fit when I had put it back together. It was tight, but just didn’t feel right.
So I looked at that while the car was running and sure enough, noticed that I could hear the engine when I put my ear up to the flex joint. There was a smaaaall gap where O2 could get in and throw the readings at the 2nd sensor! Not enough to notice a huge difference on my Bluedriver (2nd sensor was showing 0.265 volts), but enough to supposedly throw my P1273 code.
So I installed a few rings around the male pipe connector on the manifold to help lift the curved side of the flex pipe gasket out a little further to fill up that gap I was talking about. After a few rings that I had cut out of a tin sheet I was able to make it mesh good to work with the new manifold and old flex joint and pipe. Bolted it back up. Started the car. No more noise.
The car sounded better than it had in a long time! No cracks in the exhaust, no flex pipe leak!
Performed the fuel trim history clearing procedure.
Man oh man I can’t tell you how pleased I am!!!! LTFT is 7%! LTFT + STFT hovers from 7 to 9%!
Been driving the car now for a long time and no codes!!! No P0420, no P1273!
Engine purrs!

Here’s my final readings:
(range includes cold start to warm engine, at idle and 3000 RPM)
STFT 0 to 9%
LTFT 7%
O2B1 0.12 to 0.9V
O2B2 0.28 to 0.31V
So what did I learn? Here’s the main things that will change my mechanic life forever:
1. Catalytic converters should last for 200,000+ miles with a well maintained engine. If you’re cat goes bad, you probably have other problems that just haven’t thrown a code yet.
2. You can have small problems with no CELs that can turn into big ones!
3. Fuel trims can really help diagnose issues!
4. The 2nd O2 sensor is not JUST used for exhaust emissions! The ECM uses BOTH O2 sensors to determine fuel trims (and lean or rich fuel conditions).

So what did this mean for me? That I will fix catalytic converter problems much sooner from now on if I plan to keep my car around past 200,000 miles.
If your engine is running rich for a long time it can damage other parts, and eventually expensive ones. I’ll admit, emissions aren’t my biggest concern. But I do care about engine longevity.
All that said, if you have a P0420, P1273, or P1274, hopefully my story will help save you some hassle.
Take care,
Benny

thanks...is relevant, helped me solve my clients' problems.

1.7 million views guess i wont buy a nissan