Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that a part of the car that checks how clean the air is coming out of the engine isn't working right when the car slows down.
The O2 sensor is detecting values that are outside of the expected range during deceleration, indicating a potential issue with the sensor or the exhaust system.
The P239E code is triggered when the oxygen sensor located on Bank 1, Sensor 2, detects a voltage reading that is outside the normal range during deceleration. This could indicate a problem with the sensor itself, wiring issues, or exhaust leaks.
• Check Engine Light is on
• Poor fuel economy
• Rough idling
• Faulty O2 sensor
• Exhaust leak
• Wiring or connector issues
O2 Sensor: A device that measures the amount of oxygen in the exhaust gases.
Deceleration: The process of slowing down the vehicle.
• Use an OBD-II scanner to confirm the code.
• Inspect the O2 sensor and its wiring for damage.
• Check for exhaust leaks.
• Replace the faulty O2 sensor.
• Repair any exhaust leaks.
• Fix or replace damaged wiring or connectors.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford F-150
• Regularly inspect and maintain the exhaust system.
• Ensure proper functioning of O2 sensors.
• Address any exhaust leaks promptly.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Regular maintenance can prevent such issues.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
O2 sensor related codes have been common as vehicles rely on these sensors for efficient fuel management and emissions control.
Moderate – While the vehicle may still run, ignoring the issue can lead to poor fuel economy and potential damage to the catalytic converter.
Driving with a faulty O2 sensor can lead to increased emissions, which may not comply with local environmental regulations.
• Vehicle should be in a safe location.
• Engine should be at normal operating temperature.
The O2 sensor is located on the exhaust system, downstream of the catalytic converter on Bank 1.
Q: What does Bank 1 Sensor 2 mean?
A: Bank 1 refers to the side of the engine with cylinder 1, and Sensor 2 is the second sensor in the exhaust stream.
Q: Can I drive with a P239E code?
A: It's possible to drive, but it's not recommended as it can lead to further issues and increased emissions.
Budget · Enhanced code reader
A wired color-screen reader with readiness hotkeys, live data, code definitions, and data logging.
Good for emissions-related codes because it exposes readiness monitors and live powertrain data.
View on Amazon
Specialty · Smoke machine
Helpful for finding EVAP and vacuum leaks that are hard to see with visual inspection alone.
Helpful for tracking down EVAP and vacuum leaks that can trigger emissions faults.
View on Amazon
Specialty · O2 sensor socket
Helpful when the code points toward exhaust or oxygen-sensor work and space is tight.
Useful when the diagnosis points toward oxygen-sensor removal or replacement.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
Fitment Required · Vehicle-fitment part
Relevant when the code or supporting diagnostics point toward upstream or downstream oxygen-sensor faults.
This code family often involves upstream or downstream oxygen-sensor diagnosis.
Verify exact sensor position and vehicle fitment before buying.
View options on Amazon
Fitment Required · Vehicle-fitment part
Relevant when catalyst-efficiency or emissions faults persist after proper diagnosis.
Catalyst-efficiency faults sometimes point toward converter problems after proper testing.
Catalytic converters are highly vehicle-specific and should not be purchased by code alone.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.