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Discussion Starter #1 (Edited)
Hi! Does anyone know what obd code p1273 on my 2005 Murano might mean? I am finding several things it could be and would like to pinpoint it. I just took out the mass airflow sensor and sprayed it with cleaner and waiting for it to dry. Any help would be greatly appreciated. Thanks!
 

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Discussion Starter #4
I cleaned the mass airflow sensor and put a new air filter in. I cleared the code and I'm going to take it for a ride to see if the light pops back on. Hopefully this will work but I doubt it. The exhaust is pretty loud and stinky. Wondering what I should try next.
 

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I cleaned the mass airflow sensor and put a new air filter in. I cleared the code and I'm going to take it for a ride to see if the light pops back on. Hopefully this will work but I doubt it. The exhaust is pretty loud and stinky. Wondering what I should try next.
P1273: Air fuel ratio (A/F) sensor bank 1 lean shift monitoring

This means that the bank 1 A/F sensor is sending a lean signal to the PCM for too long a time period. Check STFT and LTFT in live data on your scan tool to confirm if that bank appears to be running lean.
 

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Error Code P1273 is described as Air Fuel Ratio Sensor 1 Bank 1 Lean Shift Monitoring. This refers to a lean condition due to too much oxygen, usually caused by a vacuum leak, fuel pressure, dirty MAF (Mass Airflow sensor), or defective or dirty injectors.
 

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Discussion Starter #7
P1273: Air fuel ratio (A/F) sensor bank 1 lean shift monitoring

This means that the bank 1 A/F sensor is sending a lean signal to the PCM for too long a time period. Check STFT and LTFT in live data on your scan tool to confirm if that bank appears to be running lean.
Hi! Thanks for replying. I just purchased a scanner that reads the fuel trim. The readings for stft and Ltft seem to be fine, fluctuating between -5 and+5. The light came back on after I cleaned the mass air flow sensor. Where would you go from here?
 

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You said the exhaust is louder than normal. An exhaust leak can cause your sensor to read lean.
An exhaust leak will allow fresh air to enter the system on the negative pressure side of an exhaust event, this will cause an oxygen sensor to produce a lean reading. An exhaust system manages both pressure and vacuum cycles while an engine runs.
I would check your exhaust system for leaks.
The following website has good tips and what to check when you get a lean reading.
 

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Discussion Starter #9
You said the exhaust is louder than normal. An exhaust leak can cause your sensor to read lean.
An exhaust leak will allow fresh air to enter the system on the negative pressure side of an exhaust event, this will cause an oxygen sensor to produce a lean reading. An exhaust system manages both pressure and vacuum cycles while an engine runs.
I would check your exhaust system for leaks.
The following website has good tips and what to check when you get a lean reading.
Thanks so much! I will check the exhaust next.
 

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The first gen is known to get cracked exhaust manifold. Reported by members and confirmed by one of the nissan tech residents long ago. Spraying soapy water on it while having a leaf blower or shop vac blow air from the tail pipe and plugging the other tail pipe should show if you have one.
 

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Symptoms of a Bad or Failing Exhaust Manifold Gasket
Engine exhaust manifolds are the metal components that are responsible for collecting exhaust gases and transporting them to the exhaust for expulsion from the tailpipe. They are bolted to the engine cylinder head(s) and are sealed using a gasket known as the exhaust manifold gasket.
The exhaust manifold gasket is usually a multi-layered gasket that contains metal and other materials that are designed to provide the best seal possible. As the exhaust manifold gasket is the first in the exhaust system, it is a very important seal that should be inspected if any problems arise. When it fails or has any issues, it can cause all sorts of problems for the vehicle. Usually a bad or failing exhaust manifold gasket will produce a few symptoms that can alert the driver of a potential issue.
1. Excessively noisy engine
One of the first symptoms of a problem with an exhaust manifold gasket is an excessively noisy engine. A faulty exhaust manifold gasket will produce an exhaust leak that will sound like a hissing or tapping sound coming from the engine. The sound may be especially pronounced during a cold start or during acceleration.
2. Decrease in power, acceleration, and fuel efficiency
Engine performance issues are another common symptom of a problem with an exhaust manifold gasket. If the exhaust manifold gasket fails, the exhaust leak can result in engine performance issues such as a decrease in power, acceleration, and even fuel efficiency. The performance decrease may be minor at first, but will worsen over time if not addressed.
3. Burning smell coming from the engine bay
Another symptom of a potential problem with the exhaust manifold gasket is a burning smell from the engine bay. If the gasket fails and leaks near any plastic components, or engine wiring, the heat from the exhaust gases may cause the components to burn up. This may result in a burning smell coming from the engine bay as a result of the components being exposed to such high heat.
 

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Discussion Starter #12
The first gen is known to get cracked exhaust manifold. Reported by members and confirmed by one of the nissan tech residents long ago. Spraying soapy water on it while having a leaf blower or shop vac blow air from the tail pipe and plugging the other tail pipe should show if you have one.
Is the exhaust manifold you are speaking of under the car or under the hood? I recently had a p0420 code with the 05 Altima and needed the manifold under the hood replaced. I don't think it's a cat problem due to the code. I'm going to take it to a muffler shop tomorrow and get it inspected. I'm just hoping it's not going to cost too much whatever it is.
 

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Discussion Starter #14
The notorious exhaust manifold problem has been with the rear manifold, which is underneath.
Take a look here: https://www.nissanmurano.org/threads/rear-exhaust-manifold-replacement.174274/
I think the muffler shop is the right idea. They should be able to pinpoint your issue, and hopefully it'll be on the cheap!
Good luck, and let us know how it turns out!
Thanks so much for all your help. It's great having this community to talk to. I'll update as soon as I find anything out.
 

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Yes! I finally got it to a muffler shop. I ordered the whole y pipe with the flex pipes and catalytic converter. Took it to a muffler shop and got it installed today. The piece ended up being too short so they had to make adjustments. Also, one of the oxygen sensors near the flex pipe was completely stripped and hanging. They fixed that by adding a piece of pipe with a nut welded in for the sensor to screw back in. I was so happy it was finally fixed until the service engine light popped back on when I went to pick up my son from school. I'm guessing I need to replace one of the sensors now. Probably sensor 1 bank 1 but not sure.
 

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Yes! I finally got it to a muffler shop. I ordered the whole y pipe with the flex pipes and catalytic converter. Took it to a xender discord omegle muffler shop and got it installed today. The piece ended up being too short so they had to make adjustments. Also, one of the oxygen sensors near the flex pipe was completely stripped and hanging. They fixed that by adding a piece of pipe with a nut welded in for the sensor to screw back in. I was so happy it was finally fixed until the service engine light popped back on when I went to pick up my son from school. I'm guessing I need to replace one of the sensors now. Probably sensor 1 bank 1 but not sure.
I just took out the mass airflow sensor and sprayed it with cleaner and waiting for it to dry. Any help would be greatly appreciated. Thanks!
 
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