P0140 OBD-II Trouble Code: O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0140 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0140 code

P0140 is a diagnostic trouble code (DTC) for "O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0140 DIAGNOSTIC Get a fair and transparent estimate upfront

P0140 code definition

O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)

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 cutoff or fuel enrichment signals by the Engine Control Module (ECM).

What causes the P0140 code?

  • The ECM determines that the O2 sensor has no activity

  • The O2 sensor for Bank 1, Sensor 2 does not respond (does not have a voltage change between 410-490 mV) to the fuel cutoff or fuel enrichment signals from the ECM for more than 74 seconds

  • The O2 sensor and mass airflow sensor comparison is misinterpreted by the ECM

  • The ECM could be malfunctioning in the O2 circuit

What are the symptoms of the P0140 code?

  • The Check Engine Light will come on, indicating a problem

  • Rough running

  • Hesitation (upon acceleration after a deceleration phase)

  • The ECM loses the ability to keep the fuel system air-to-fuel ratio correct (could cause erratic driving symptoms)

How does a mechanic diagnose the P0140 code?

  • Scans codes and documents freeze frame data

  • Monitors the O2 sensor data to see if the voltage is is moving above or below 410-490 mV

  • Monitors the mass airflow sensor data for responses to throttle changes, per specifications

  • Follows the manufacturer's specific pinpoint tests for further diagnosis of the code (tests differ between manufacturers)

Common mistakes when diagnosing the P0140 code?

  • Check the mass airflow sensor for proper operation and contamination before replacing the O2 sensor.

The no response of the O2 sensor can be caused by a mass airflow sensor being contaminated and not calculating the amount of air entering the engine on the intake side.

How serious is the P0140 code?

  • This code can be due to problems with the mass airflow sensor, which is needed to calculate the proper amount of air entering the engine. Along with the O2 sensors, failure of any of these components will cause the ECM to miscalculate the air/fuel ratio going into the engine.

  • The ECM can lose control or get the wrong input from sensors like the mass airflow sensor or the O2 sensor if they are within specification but incorrect.

These problems can cause erratic drive complaints, which can compromise a driver's safety.

What repairs can fix the P0140 code?

After scanning and clearing all fault codes and verifying the failure:

  • 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
  • Clean out the mass airflow sensor to see if readings change

Additional comments for consideration regarding the P0140 code

The no response of an O2 sensor may be due to a mass airflow sensor that is contaminated from things like oil from an oil impregnated air filter, as is common to all sensors. This oil coats the sensor and can cause it to become inaccurate. Cleaning the sensor may or may not fix the problem.

Need help with a P0140 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

P0140
Check Engine Light
trouble codes

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0140 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

4,743

Rating Summary
4,361
185
47
28
122
4,361
185
47
28
122

Oreste

12 years of experience
108 reviews
Oreste
12 years of experience
Nissan Altima - Check Engine Light is on - Hialeah, Florida
Showed up quick, and went straight to inspecting a brake light on the dash issue. He found the issue, fixed it, and showed me exactly what was wrong. Thank you!

Daniel

9 years of experience
58 reviews
Daniel
9 years of experience
Honda Fit - Check Engine Light is on - Chicago, Illinois
Told me everything I needed to know and switch out after the inspection. So, I scheduled another service the next day for all the fixes, or fluid maintenance.

Patrick

31 years of experience
1032 reviews
Patrick
31 years of experience
Hyundai Santa Fe - Check Engine Light is on - Austin, Texas
Even after working on my car, he took the time to explain what he did, the parts, and any next steps. Very knowledgeable!

Joe

12 years of experience
22 reviews
Joe
12 years of experience
Toyota 4Runner - Check Engine Light is on - Sacramento, California
Joe was very thorough in his inspections, and his knowledge & experience was clear in his explanations of what was wrong with my car. I really appreciated his recommendations, and the fact that he worked so efficiently that it cut down on time... I would definitely book with him again.

More related articles

P0121 OBD-II Trouble Code: TPS "A" Circuit Range Performance Problem
P0121 code definition Throttle Pedal Position Sensor/Switch (TPS) A Circuit Range Performance Problem What the P0121 code means P0121 is a generic...
How to Transfer a Car Title in Idaho
In In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs to be transferred into the new owner’s name. The state of Idaho has...
Rules of the Road For Iowa Drivers
Driving Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in your own state, that does not mean you know them in all...

Related questions

Are the variable valve timing solenoid and the camshaft sensor the same?

Hello. The variable valve timing and the camshaft position sensor are two separate sensors. The camshaft position sensor is more towards the front of the engine and is a lot easier to replace. The variable valve timing sensor is a...

Maintenance warning light - 2006 Toyota Corolla

Hello. For most Toyota vehicles the maintenance required light is different from the Check Engine Light, and come on during different circumstances. The Check Engine Light is usually the more serious of the two, and comes on when the computer...

P0030 p0015 chk eng lgt on whining noise stuck 2 gear 1 yr had car let son drive 2 NV havent chk fluid N trans hope it wasnt low

The code P0015 is a bank 1 timing over retarded warning. The P0030 code stands for the heated oxygen sensor malfunction, which also pertains to bank 1. The oxygen sensor malfunction could be due to a failed sensor, heater, or...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com