Shop Parts keyboard_double_arrow_right
Need car parts? Select your vehicle
Reading Time: 5 minutes
Summary
  • The diagnostic trouble code (DTC) P0143 stands for “O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3).”
  • The powertrain control module (PCM) will log the P0143 code if it detects a lower-than-normal signal voltage from the bank 1, sensor 3 post-catalytic converter oxygen sensor or its circuit.
  • Common causes of the P0143 code are air leaks in the exhaust, a bad oxygen sensor, and wiring issues.
  • The P0143 code’s symptoms are an illuminated check engine light and poor engine performance.

The P0143 code is one of many trouble codes that may be logged by your vehicle’s primary computer. Read on to learn about what it involves, its potential triggers, and common symptoms.

What Does the P0143 Code Mean?

Diagnostic trouble code (DTC) P0143 stands for “O2 Sensor Circuit Low Voltage Bank 1 Sensor 3.” It is logged when the powertrain control module (PCM) detects a potential problem with the bank 1, sensor 3 post-catalytic converter (catcon) oxygen sensor or its circuit.

P0143 trouble code
Code P0143 may register if the PCM detects a potential problem with the bank 1, sensor 3 post-catcon oxygen sensor or its circuit.

Depending on the vehicle configuration, “bank 1” may refer to the side of the engine that contains cylinder 1. “Sensor 3” refers to one of the oxygen sensors located downstream of the catalytic converter.

See also  Common Questions Asked by Motorists

The oxygen sensor located at the rear of the catalytic converter (bank 1, sensor 3) measures the catcon’s efficiency in controlling emissions. The PCM uses this information to determine if the converter is in working condition.

A functional post-cat sensor will exhibit voltage differences at a slower rate than the front oxygen sensors. It typically indicates a low switching frequency between the two sensors. However, if the PCM perceives the signal voltage from the post-cat oxygen sensor to be lower than factory specifications, it will set error code P0143.

There’s more information that can help you fix P0143 in our advanced discussion about the downstream oxygen sensor.

Note: The definition of code P0143 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0143 Code?

P0143 is a generic code, so it can have many triggers. Here are the most common:

mechanic checking vehicle chassis
Air leaks in the exhaust that result in false readings are a possible cause of code P0143.

What are the Common Symptoms of the P0143 Code?

You may notice the following symptoms if you drive a car that has a logged P0143 engine code:

How to Diagnose the P0143 Code

Although the P0143 engine code may have similar triggers and symptoms to other DTCs, there is no universal fix for this code. Vehicles are built differently depending on the manufacturer, so the code’s exact diagnostic and repair procedures may vary.

See also  P0132: Oxygen Sensor Circuit High Voltage (Bank 1, Sensor 1)

If you’re not an advanced DIYer, don’t attempt to diagnose the code on your own. It might be best to leave the diagnosis to a professional.

How to Fix the P0143 Code

Code P0143 may be set in vehicles of varying makes and models. It may also share similar causes and symptoms with other DTCs. However, since vehicle designs differ per manufacturer, there is no single, fail-safe solution for this code.

Always refer to the factory repair information specific to your car before DIY-ing any repairs. For instance, a solution that worked for a P0143 on a Chevy Suburban might not work for a P0143 on a Toyota Sequoia.

If you aren’t confident in your automotive know-how, it may be best to bring your vehicle to an auto shop for proper diagnosis and repair.

Replace Your Faulty Oxygen Sensor Today

Diagnostic trouble codes like P0143 are not meant to be ignored. Unless you want the problem to get worse, you should address the issue head-on by replacing the faulty oxygen sensor causing it. Luckily, getting a replacement oxygen sensor is fast and easy with CarParts.com. 

CarParts.com offers a wide selection of high-quality oxygen sensors that you can easily browse with the help of our built-in vehicle selector and search filters. We want to take the guesswork out of shopping for auto parts, so we provide accurate and detailed fitment information for each product. In case you aren’t completely satisfied with your order, you can also avail of our 60-day return policy. We’ll give you your money back as long as you return your order within 60 days of your purchase.

See also  P0137 Code: Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2)

Don’t wait until your faulty oxygen sensor starts affecting your engine’s performance before replacing it. Check out our wide selection of oxygen sensors at CarParts.com and get a replacement today!

Products Mentioned in this Guide

Shop this Project

DriveWire – Oxygen Sensor, 4-Wire, Heated, With Female Connector
, P0143 Code: O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
$24.49 Price and rating may change from the time content is published.
DriveWire – Oxygen Sensor, 4-Wire, Heated
, P0143 Code: O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
$51.99 Price and rating may change from the time content is published.
About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : OBD-II Trouble Codes Tagged With :
Aries AscentStep Running Board Kit Rebate
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments
expand_more
CarParts.com Answers BE PART OF OUR COMMUNITY: Share your knowledge & help fellow drivers Join Now
The owner of this website has made a commitment to accessibility and inclusion, please report any problems that you encounter using the contact form on this website. This site uses the WP ADA Compliance Check plugin to enhance accessibility.