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

Repair Importance Level: 3/3
Repair Difficulty Level: 2/3   
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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

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 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).

OBDII Code P1273 - Air Fuel Ratio Sensor 1 Bank 1 Lean Shift Monitoring - AutoCodes.com

P1273 Information for specific makes

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