P0156 OBD-II Trouble Code: 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0156 code

P0156 is a diagnostic trouble code (DTC) for "02 Sensor Circuit Malfunction (Bank 2 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 P0156 DIAGNOSTIC Get a fair and transparent estimate upfront

P0156 trouble code definition

Oxygen Sensor Circuit Malfunction (Bank 2 Sensor 2)

What the P0156 code means

The purpose of the oxygen sensor is to monitor the amount of oxygen present in the exhaust and relay this information to the power control module (PCM). As the amount of oxygen increases or decreases, the oxygen sensor fluctuates between a low voltage and a high voltage.

If the oxygen sensor remains at a low voltage for an extended period of time, or is simply not active at all, the P0156 trouble code will be stored by the power control module (PCM) and the Check Engine Light will come on as an indication to the driver that there is a problem in the engine.

What causes the P0156 code?

  • Gas leaks in the exhaust
  • Air leaks in the intake
  • Defective fuel injectors
  • Broken or exposed wires
  • Voltage wires or circuits that have shorted out
  • Exhaust holes that are located near or around the oxygen sensor
  • Engine vacuum leaks
  • Oxygen sensor wires touching the exhaust

What are the symptoms of the P0156 code?

Drivers may not notice any symptoms associated with the P0156 trouble code. The Check Engine Light will come on, which is the most noticeable symptom, and there may be a loss of fuel economy. The vehicle will also have an increase of pollutants that it is emitting into the environment.

How does a mechanic diagnose the P0156 code?

  • An OBD-II scanner is used to make a record of all trouble codes that have been stored by the power control module (PCM).

  • The oxygen sensor live data on the OBD-II scanner is reviewed to make an observation as to whether the oxygen sensor is working properly.

  • They will be able to make a conclusion by noting whether the oxygen sensor is switching from low voltage to high voltage as it should.

  • Using the OBD-II scanner, they will view live data for the fuel injectors to make sure they are working properly.

  • The oxygen sensor wiring will be inspected for shorted, broken, or exposed wires.

  • The engine will be checked for escaping air. This could be an indication of vacuum leaks or broken vacuum lines and then exhaust will be inspected for holes.

Common mistakes when diagnosing the P0156 code

  • The mistake that is most commonly made when diagnosing the P0156 trouble code is automatically replacing the oxygen sensor without inspecting any other component. The oxygen sensor is not always the problem, and replacing it does not always remedy the problem.

  • Consideration should be given to the condition of the wiring, exhaust, vacuum lines, intake and fuel injectors.

How serious is the P0156 code?

This code is not generally considered a serious one. However, the driver may experience an increase of fuel consumption and while in this condition, and the vehicle will let off more pollutants into the environment.

What repairs can fix the P0156 code?

Additional comments for consideration regarding the P0156 code

At times, depending on the vehicle, the oxygen sensor may be hard to reach. An oxygen sensor set may be needed to remove the sensor. It is also common for the oxygen sensor to cease up in the exhaust and to be removed properly by a heating element, such as a propane torch, in addition to the oxygen sensor set.

Need help with a P0156 code?

YourMechanic offers certified 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 to help resolve this issue.

trouble codes
Check Engine Light
P0156

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0156 code.

SCHEDULE P0156 DIAGNOSTIC
Get a $20 credit for the follow-up repair

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

5,170

Rating Summary
4,765
197
50
27
131
4,765
197
50
27
131

Fred

16 years of experience
364 reviews
Fred
16 years of experience
Mercedes-Benz E500 - Check Engine Light is on - Conroe, Texas
Fred was very friendly and thorough to get to the root of the issue. Even when he could not find a fault to why my engine light was on, he went above and beyond to make absolutely sure that the concern was minimized. Turns out, all that needed to be done was a reset but his diagnostic to address my issues was very intricate and appreciated.

David

17 years of experience
37 reviews
David
17 years of experience
Chevrolet Cruze - Check Engine Light is on - Aurora, Colorado
David was on time, professionalisms & honest! I would definitely request him again and pass along to friends/family.

John

18 years of experience
18 reviews
John
18 years of experience
Dodge Ram 1500 - Check Engine Light is on - Memphis, Tennessee
Demonstrated good integrity. Advised me when work I thought needed done was unnecessary and was helpful in identifying issues that needed to be addressed

Robert

21 years of experience
17 reviews
Robert
21 years of experience
Chrysler 200 - Check Engine Light is on - Fort Worth, Texas
Robert did a good job working on my car and letting me know what's needed to keep my car driving smoothly.


Related questions

My check engine light came on. Took it to Autozone and they came up with this code PO156. What is that

Hello, thank you for writing in. A P0156 troubleshooting code stands for an error with the oxygen sensor. There are multiple sensors, and this one is behind (further towards the rear) the catalytic converter. Several things may be happening. First,...

More related articles

P3475 OBD-II Trouble Code: Cylinder 10 Deactivation/Intake Valve Control Circuit Low
P3475 means a malfunction in engine cylinder number 10 in which the vehicle will be unable to run in lower modes and may cause lower fuel efficiency.
P0579 OBD-II Trouble Code: Cruise Control Multi-Function Input A Circuit Range/Performance
P0579 P0579 OBD-II Trouble Code: Cruise Control Multi-Function Input A Circuit Range/Performance P0579 code definition The P0579 code signifies that the car’s computer has found a malfunction in the cruise control multi-function input A circuit. What the P0579 code...
P0015 OBD-II Trouble Code: Camshaft Position B - Timing Over-Retarded (Bank 1)
P0015 code definition Camshaft Position “B” - Timing Over-Retarded (Bank 1) What the P0015 code means P0015 is the OBD-II generic code...

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 (855) 347-2779 · hi@yourmechanic.com