P1273 Nissan Code: A/F Issues And Lean Condition

If you’re a Nissan vehicle owner who has encountered the P1273 error code, you’ve come to the right place. This code indicates specific air/fuel (A/F) issues and a lean condition within your vehicle’s system. This comprehensive guide will provide valuable insights into the meaning, severity, symptoms, causes, diagnosis, and repair of the P1273 Nissan code.

Whether you’re an experienced car enthusiast or a novice owner, we’ve got you covered. We’ll break down the technical aspects and equip you with practical knowledge to confidently address this issue. Read on! 

P1273 Nissan Code: A Quick Summary

Take a quick look at the key information of the P1273 Nissan code!

  • Definition: Air Fuel Sensor (Bank 1 Sensor 1) Circuit Lean Shift
  • Severity: Medium
  • DIY Skill Level: Intermediate
  • Continue To Drive?: Yes
  • Estimated Repair Cost: $100 – $400

What Does P1273 Nissan Code Mean

The P1273 error code on Nissan refers to a potential issue in the fuel system. When this code is triggered in your car, it indicates a lean running condition, specifically related to the operation of air-fuel ratio sensor 1 on bank 1.

In other words, the engine control module (ECM) has detected an imbalance in the air-fuel mixture, which can impact engine performance. To understand this code better, let’s explore the components involved and how they interact.

P1273 Nissan diagram
The (A/F) sensor, commonly located near the exhaust manifold, plays a critical role in engine performance and can trigger the P1273 Nissan code if it malfunctions. (Image credit: Nissanhelp.com)

The air-fuel ratio sensor, also known as the A/F sensor, plays a crucial role in measuring the oxygen content in the exhaust gases. It provides feedback to the ECM to ensure the optimal air-fuel mixture (14.7:1 stoichiometric ratio) for combustion. In Bank 1, the ECM monitors the air-fuel ratio for any deviations from the expected values.

In certain conditions, such as during acceleration or deceleration, the ECM monitors lean-to-rich or rich-to-lean shifts. If the ECM detects a lean shift that persists beyond the specified parameters, it triggers the P1273 code.

It’s important to note that the P1273 code is commonly found in Nissan models such as Altima, Murano, Pathfinder, Sentra, Frontier, Quest, and 350Z. Altima, particularly the 2004 and 2005 models, is notorious for experiencing this code frequently.

Furthermore, there are other associated codes that may accompany P1273, including P1283, P0174, and various A/F sensor codes such as P0036, P0037, P0038, P0042, P0043, P0044, etc.

How Serious Is The P1273 Nissan Code?

The P1273 Nissan code is considered a medium-level severity. While it may not immediately cause a breakdown or severe damage to your vehicle, it should not be ignored. You can continue to drive with the code in the short term, but it is important to address it promptly.

P1273 Nissan
P1273 pops up! Get it addressed ASAP!
(Image credit: 350Z UK Forum)

Prolonged driving with the P1273 code may result in reduced fuel efficiency, decreased engine performance, and possible damage to the catalytic converter over time. Ignoring the code can also trigger additional related codes, complicating the diagnosis and repair process.

Read more: Nissan Trouble Codes: Comprehensive List For OBD1/OBD2

P1273 Nissan: Spotting the Telltale Signs

When encountering the P1273 Nissan error code, several symptoms may manifest:

  • Service engine light illuminated
  • Engine hard to start in cold conditions
  • Fuel smell
  • Mode $06 fault
  • Engine starts up but won’t stay on and stalls

However, in some cases, the vehicle may drive well with no noticeable drivability symptoms.

Read more: Nissan Dashboard Warning Lights and Meanings (FULL list, FREE Download)

Root Causes Of P1273 Nissan Code

Some common culprits behind the P1273 code include:

  • Poor connection or wiring issues related to the A/F sensor
  • Open or short circuit conditions in the A/F sensor circuit
  • Failed air-fuel ratio sensor (A/F sensor) 
  • Vacuum leaks in the intake system
  • Issues with the fuel delivery system, such as a clogged fuel filter or weak fuel pump
  • Defective MAF sensor
  • Malfunctioning ECM (rarely)


Please remember that the above causes are general and commonly associated with the P1273 code in Nissan vehicles. However, it’s essential to remember that the underlying causes may vary in specific cases. 

For instance, based on my experience, I’ve encountered situations where issues with coolant quality and leakage into the engine have been identified as contributing factors. The story from member Stealthm in this forum thread is an example. 

Efficient Strategies For Resolving The P1273 Nissan Code

In this section, we will provide step-by-step instructions and a list of essential tools and parts needed to address the issue. By following this guide, you can effectively identify and resolve the C1130 code.

Essential Tools And Parts

To diagnose and repair the P1273 code in a Nissan, you will need the following tools and parts:

Step-by-Step Procedure

1. Retrieve DTCs

Connect an OBD-II scanner to your Nissan vehicle and retrieve all trouble codes, including P1273. Note any additional codes present. Prioritize addressing the codes directly impacting the air-fuel ratio sensor or related systems.

2. Inspect wiring related to A/F sensor 

Inspect the engine bay for damaged or loose wiring related to the air-fuel ratio sensor. Check for disconnected or worn vacuum hoses. 

3. Check for circuit issues

Examine the A/F sensor circuit for open or short circuits. Inspect wiring harnesses and connectors. Repair or replace damaged wires or connectors.

4. Test the air-fuel ratio sensor

Measure the sensor’s resistance and voltage output using a multimeter or diagnostic tool. Compare readings to specified values in the service manual. Replace the sensor if it fails the test.

5. Inspect the intake system

Check for vacuum leaks in the intake system. Inspect gaskets, hoses, and components. Repair or replace faulty parts.

6. Check fuel pressure

Measure fuel pressure on the fuel rail (aim for at least 55 psi). If pressure is low, check the fuel pressure regulator, fuel filter, and fuel pump for issues. Repair or replace as needed.

7. Check MAF sensor and intake plumbing

Inspect the MAF sensor for dirt or debris. Clean it if necessary using MAF sensor cleaner. Check clamps and connections between the MAF sensor and throttle body for leaks or looseness.

8. Inspect the ECM 

If the previous steps don’t resolve the issue, inspect the engine control module (ECM). Ensure proper connections and check for loose or damaged wires. Consult a professional if ECM malfunction is suspected.


  • Follow the manufacturer’s instructions and any additional notes or tips in the service manual for your vehicle model.
  • The A/F sensor location may vary depending on the specific Nissan model and engine type. To find the precise location of the A/F sensor in Nissan, refer to the vehicle’s manual or visit reliable online sources such as this diagram for A/F sensor location in Nissan Altima.
Let’s watch this video to see how to check the A/F sensor and fix the P1273 code on the Nissan Altima.

DIY Repair Level And Estimated Costs

The DIY repair level for diagnosing and fixing the P1273 code in a Nissan is moderate. It requires basic mechanical knowledge and the ability to use diagnostic tools and perform sensor replacement.

The estimated cost for this repair task may vary depending on factors such as the brand and quality of the A/F sensor, labor rates in your area, and whether you choose to do the repair yourself or seek assistance from a professional mechanic.

Here is a table listing the estimated costs for the main repair tasks:

Repair TaskEstimated Cost Range
Diagnostic $50 – $150
Wiring repair$50 – $200
A/F sensor repair/replacement$200 – $400
Intake system components repair/replacement $100 – $300
Fuel delivery system components repair/replacement$100 – $300
MAF sensor repair/replacement$100 – $300
ECM repair/replacement$200 – $1000

P1273 Nissan Infographic

P1273 Nissan
Check this infographic for the summarized information about this P1273 code on Nissan vehicles.

Final Thoughts

In conclusion, understanding and addressing the P1273 code in Nissan vehicles can help ensure optimal engine performance and fuel efficiency. By following the general diagnostic and repair steps outlined, you can effectively troubleshoot and resolve issues related to the Air/Fuel Ratio (A/F) sensor or its circuit.

If you found this information helpful, share it with others who may benefit from it. Additionally, we would love to hear from you if you have any comments, questions, or personal experiences related to the P1273 code.

For information on other OBD2 codes and to troubleshoot specific issues with your vehicle, visit our OBD code lookup tool

Safe travels and happy diagnosing!

Reference Sources

  1. Nissan Help Forum, P1273 – Nissan
  2. My350z Forum, What does code P1273 mean?
  3. YourMechanic, After oxygen sensor replacement I’m getting a P1273 error…
  4. Reddit, Question about code P1273 and P0174

About The Author

Leave a Comment

Your email address will not be published. Required fields are marked *