Engine-CodesInfiniti – P1278 Infiniti

P1278 Infiniti Code - Air Fuel Ratio Sensor 1 Bank 1 Circuit Slow Response

Quick Answer

The P1278 code for Infiniti vehicles specifically relates to the Air Fuel Ratio (A/F) Sensor 1 on Bank 1 having a slow response. Common causes include Faulty A/F sensor, Wiring issues or corrosion in the sensor circuit, Vacuum leak. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1278 Infiniti indicates Air Fuel Ratio Sensor 1 Bank 1 Circuit Slow Response.
Common causes
Common causes include Faulty A/F sensor, Wiring issues or corrosion in the sensor circuit, Vacuum leak.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P1278 Infiniti Description

The P1278 code for Infiniti vehicles specifically relates to the Air Fuel Ratio (A/F) Sensor 1 on Bank 1 having a slow response. The A/F sensor is responsible for monitoring the air-fuel mixture in the exhaust gases exiting the engine. It provides feedback to the engine control module (ECM) to ensure the engine is running efficiently. When the A/F sensor on Bank 1 (which typically refers to the side of the engine where cylinder 1 is located) has a slow response, it means that the sensor is not reacting quickly enough to changes in the air-fuel ratio. This can lead to poor engine performance, decreased fuel efficiency, and increased emissions.

OBDII Code P1278 Infiniti - Air Fuel Ratio Sensor 1 Bank 1 Circuit Slow Response
P1278 Infiniti Code - Air Fuel Ratio Sensor 1 Bank 1 Circuit Slow Response

Common Causes of P1278 Infiniti

  1. Faulty A/F sensor
  2. Wiring issues or corrosion in the sensor circuit
  3. Vacuum leak
  4. Exhaust leak near the sensor
  5. ECM malfunction

Symptoms of P1278 Infiniti

  1. Rough idling
  2. Hesitation or stumbling during acceleration
  3. Decreased fuel economy
  4. Illuminated check engine light

How to Fix P1278 Infiniti

  1. Diagnose the issue by using a scan tool to read the code and monitor the A/F sensor's response in real-time.
  2. Inspect the A/F sensor and its wiring for any signs of damage or corrosion. Replace the sensor if necessary.
  3. Check for vacuum leaks and repair as needed.
  4. Inspect the exhaust system for any leaks near the A/F sensor and repair as necessary.
  5. Clear the code with the scan tool and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1278 Infiniti

The cost of repairing a P1278 code on an Infiniti vehicle can vary depending on the exact cause of the issue. In general, the cost of replacing an A/F sensor can range from $150 to $300, including parts and labor. Additional costs may be incurred if wiring repairs or other components need to be replaced. It's important to consult with a qualified mechanic to get an accurate estimate based on the specific circumstances of the vehicle. Labor rates at auto repair shops can vary, so it's advisable to inquire about rates in your local area for a more precise cost estimate.

When is the Code Detected?

The response (from RICH to LEAN) of the A/F signal computed by ECM from A/F sensor 1 signal takes more than the specified time.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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