Possible causes

Harness or connectors (The A/F sensor 1 circuit is open or shorted.)

Air fuel ratio (A/F) sensor 1

Air fuel ratio (A/F) sensor 1 heater

Fuel pressure

Fuel injector

Intake air leaks

Exhaust gas leaks

PCV

Mass air flow sensor

When is the code detected?

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

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1289 Description

The 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 – 800C (1,292 – 1,472F).

P1289 Information for specific makes

P1289 DODGE
P1289 FORD
P1289 INFINITI
P1289 NISSAN