What the P0140 code means?

P0140 is the OBD-II generic code which indicates that the O2 sensor for Bank 1, Sensor 2 failed respond to the fuel cut off or fuel enrichment signals by the Engine Control Module

What causes the P0140 code?

1. Shorted heater circuit in O2 sensor

2. Shorted signal circuit in O2 sensor

3. Melting of harness connector or wiring due to contact with exhaust system

4. Water intrusion in harness connector or PCM connector

5. Bad PCM

What are the symptoms of the P0140 code?

These could include a lean or rich condition in the engine, decreased fuel efficiency, black smoke from the
tailpipe, and an illuminated service engine soon lamp.

Common mistakes when diagnosing the P0140 code?

Technicians report replacement of oxygen sensors, when lean or rich engine conditions are the cause of
incorrect readings, is fairly common. Replacement of the incorrect oxygen sensor is also a possibility.

What repairs can fix the P0140 code?

Test the O2 sensor to see if it changes when the fuel mixture is enriched

Test the mass airflow sensor for the proper readings per specifications

Replace the O2 sensor if contaminated or fails tests

Replace the mass airflow sensor if contaminated or fails tests