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P1273 2005 NISSAN SENTRA - Air Fuel Ratio Sensor 1 Bank 1 Lean Shift Monitoring

Possible causes
- Faulty Air fuel ratio (A/F) Sensor 1 Bank 1
- Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
- Air fuel ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection
- Fuel pressure
- Faulty Fuel injector
- Faulty Air Flow Meter
What does this mean? What does this mean?
Tech notes
If one or more sensors are replaced the Engine Control Module (ECM) Mixture Ratio Self-Learning clearing procedure must be perform.

Sentra ECM Self-Learning procedure

What does this mean? What does this mean?
When is the code detected?
The A/F signal computed by ECM from the A/F sensor 1 signal is shifted to the lean side for a specified period.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible rough engine idle
P1273 2005 Nissan Sentra Description

The Air Fuel Ratio (A/F) sensor is a planar dual-cell limit current sensor. The sensor element of the A/F sensor is the combination of a Nernst concentration cell (sensor cell) with an oxygen-pump cell, which transports ions. It has a heater in the element.

The sensor is capable of precise measurement λ= 1, but also in the lean and rich range. Together with its control electronics, the sensor outputs a clear, continuous signal throughout a wide λ range (0.7 < λ < 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 oxygen-pump cell so that the composition of the exhaust gas in the diffusion gap remains constant at λ = 1. Therefore, the 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).

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