Possible causes

– Faulty Air fuel ratio (A/F) sensor 1 Bank 1
– Faulty Air fuel ratio (A/F) sensor 1 heater Bank 1
– Fuel pressure
– Faulty Fuel injector
– Intake air leaks
– Faulty Air Flow Meter

Tech notes

If one or more sensors are replaced the Engine Control Module (ECM) Mixture Ratio Self-Learning clearing procedure must be perform.

There is a factory service bulletin for the following Infiniti models:

2003-2012 FX
2002 G20
2003-2006 G35 Sedan
2003-2007 G35 Coupe
2006-2012 G37 Sedan
2008-2012 G37 Coupe
2002-2004 I35
2004-2012 M
2002-2006 Q45
2002-2003 QX4
2004-2012 QX56
Infiniti Factory Service Bulletin OBDII Code P1273

When is the code detected?

The output voltage computed by ECM from the A/F sensor 1 (Bank 1) signal is shifted to the lean side for a specified period.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Possible rough engine idle

P1273 INFINITI 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