Shop Parts keyboard_double_arrow_right
Need car parts? Select your vehicle
Reading Time: 5 minutes
  • The P013B code stands for “O2 Sensor Slow Response–Lean to Rich (Bank 1, Sensor 2),” which means the powertrain control module (PCM) detects that oxygen sensor 2 in bank 1 is taking too long to switch from rich to lean.
  • A malfunctioning O2 sensor, wiring issues, and a broken catalytic converter are some possible causes of the P013B code.
  • Common symptoms of the P013B code include an illuminated check engine light, poor engine performance, and poor fuel mileage.

On-board diagnostic (OBD) codes are designed to help you or your mechanic identify possible problems in your vehicle. They can be retrieved with a scan tool, though knowing what they mean is another thing. Before attempting any fixes to resolve them, you should first understand the meaning, triggers, and symptoms of the logged code.

What Does the P013B Code Mean?

Diagnostic trouble code (DTC) P013B stands for “O2 Sensor Slow Response – Lean to Rich (Bank 1, Sensor 2).” This code is logged once the powertrain control module (PCM) detects that oxygen sensor 2 in bank 1 of the engine is taking longer than expected to switch from rich (a higher output voltage) to lean (a lower output voltage).

obd code P013B
Code P013B means that the oxygen sensor 2 in bank 1 of the engine is taking longer than expected to switch from rich (a higher output voltage) to lean (a lower output voltage).

“Bank 1” refers to the side of the engine where cylinder 1 is located. “Sensor 2” refers to the downstream oxygen sensor located after the catalytic converter.

See also  P0037 Code: Heated Oxygen Sensor Heater Control Circuit Low (Bank 1, Sensor 2)

Oxygen (O2) sensors keep track of the oxygen levels in the air that enters and exits the catalytic converter. These sensors send data to the PCM, which will be used for post-catalyst monitoring and fuel control. Each oxygen sensor compares the oxygen content of ambient air with the oxygen content in the exhaust stream. For the sensor to provide an accurate reading, it has to reach optimal operating temperature.

During start-up, the PCM is in open loop, disregarding the voltage signal from the oxygen sensor. Once the sensor reaches operating temperature and closed loop is achieved, it generates voltage within a certain threshold. This voltage fluctuates depending on whether the exhaust stream is lean or rich. A typical zirconia oxygen sensor generates a higher voltage when the mixture is rich and a lower voltage when the mixture is lean.

If the PCM perceives that the oxygen sensor is taking too long to change its signal from a lower voltage to a higher voltage, it logs error code P013B.

Other DTCs may also be stored alongside it, such as P013A, P013C, P013D, P014C, P014D, P014E, and P014F.

Note: The definition of code P013B may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

faulty o2 sensor
A malfunctioning oxygen sensor is a possible cause of code P013B.

What are the Possible Causes of the P013B Code?

P013B is a generic code, so it can have many causes. Here are the most common:

See also  Emission Control Systems

What are the Common Symptoms of the P013B Code?

You may notice the following symptoms on a vehicle that has set a P013B trouble code:

poor fuel mileage p013b
Poor fuel mileage can be a sign that your vehicle is running with the P013B code.

How to Diagnose the P013B Code

Code P013B that points to a problem with the downstream O2 sensor (2/2 or 1/2), which is already supposed to be lazier than the upstream sensor on a system where the catalyst is storing oxygen correctly. If you have some DIY automotive troubleshooting experience, you can try diagnosing the problem using a scan tool record utility.

Take note that to avoid complications, code P013B should be resolved immediately. However, since it has many possible triggers, it may be difficult to pinpoint the exact cause of the problem. Always refer to the repair manual specific to your vehicle before attempting diagnosis. All vehicles are built differently, so their diagnostic processes may vary.

For instance, a P013B on a Saturn Vue may be diagnosed differently from a code P013B on a Chevrolet Cruze. As such, always refer to a repair manual before attempting anything. But if reading it has only left you confused, it might be best to leave the diagnosis to an expert.

How to Fix the P013B Code

Code P013B may be set in vehicles of varying makes and models. It may also share similar causes and symptoms with other DTCs. However, sharing similar symptoms does not mean a single solution will work across different makes and models.

Always refer to the factory repair information specific to your vehicle before DIY-ing any repairs. And if you aren’t confident in your automotive repair skills, have a technician do it for you. Just bring your car to an auto repair shop to receive the appropriate diagnosis and fix.

See also  P0136 Code: O2 Sensor Circuit (Bank 1, Sensor 2)

Products Mentioned in this Guide

About The Authors
Written By Automotive and Tech Writers

The 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's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at

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 :
headlights and components
Notify of
Inline Feedbacks
View all comments
Donald York

Thanks for the informational video’s.

View all Questions & Answers

expand_more Answers BE PART OF OUR COMMUNITY: Share your knowledge & help fellow drivers Join Now