P0156 Severity
Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.
For a proper diagnosis, RepairPal Certified shops have the equipment, tools, and expertise.
Moderate severity codes might not threaten the vehicle's safety or functionality immediately, but you should still get it diagnosed within a reasonable time frame to keep your car running well.
The purpose of the oxygen sensor is to measure the oxygen content in the exhaust gases after they leave the combustion process of the engine. This information is critical to the PCM's ability to maintain efficient fuel economy. When the PCM detects a failure of the sensor or the information received from the sensor, it will set code P0156.
RepairPal Car Genius™ is a free resource for vehicle owners seeking advice on maintenance, auto repair, shop inquiries, estimates, and finding a trustworthy repair shop in your area.
Call us at 877-913-1554
Available 9am – 6pm ET Monday through Friday
The Rear Catalyst Monitoring Oxygen Sensor evaluates the Catalytic Converter's emissions-reducing capability. Code P0156 is set when the Rear Oxygen Sensor signal does not show enough activity to indicate fuel control and closed loop fuel management.
*Reduced deductible is not valid for any extended service plans purchased in Oregon or Washington.
**The minimum 12 month/12,000 mile warranty is provided by the RepairPal Certified shop, and is subject to exclusions, including but not limited to normal wear and tear items (such as tires, brake pads, clutches, wiper blades, etc.), wheel alignments and scheduled maintenance. For additional details, terms and conditions, please refer to your selected RepairPal Certified shop’s warranty at the time of purchase. CarMax is not responsible for the price guarantee/warranty, the repair guarantee or any charges or costs pertaining to the repair of your vehicle.
RepairPal Certified Shops are third-party service providers, and they are not owned or controlled by CarMax. RepairPal Certified Shops do not perform repairs under CarMax’s Limited Warranty, and they are not necessarily affiliated with specific vehicle manufacturers. CarMax receives compensation for this relationship.