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 the car's computer found a problem with the oxygen sensor in the exhaust system when the car was slowing down. It's like the sensor is not working right when you take your foot off the gas.
The O2 sensor measures the amount of oxygen in the exhaust gases. During deceleration, the sensor should show a specific range of values. If it doesn't, the computer logs this code.
P239F indicates that the oxygen sensor located on Bank 2, Sensor 2, has readings that fall outside the expected range during deceleration. This could be due to a faulty sensor, wiring issues, or an exhaust leak.
• Check Engine Light is on
• Poor fuel economy
• Rough idling
• Increased emissions
• Faulty oxygen sensor
• Wiring or connector issues
• Exhaust leak
• Faulty PCM (Powertrain Control Module)
O2 Sensor: A device that measures the oxygen level in the exhaust gases.
PCM: Powertrain Control Module, the vehicle's main computer.
• Use an OBD-II scanner to confirm the code
• Inspect the wiring and connectors for damage
• Check for exhaust leaks
• Test the oxygen sensor functionality
• Replace the faulty oxygen sensor
• Repair or replace damaged wiring/connectors
• Fix any exhaust leaks
• Reprogram or replace the PCM if necessary
• OBD-II scanner
• Multimeter
• Wrench set
• Jack and stands
$150 - $400
Moderate
• Toyota Camry
• Ford F-150
• Honda Accord
• Regularly inspect and maintain the exhaust system
• Ensure proper sensor installation
• Use high-quality fuel
Sensor Issue
• Avoid ignoring the Check Engine Light
• Get the vehicle inspected by a professional
• Monitor fuel efficiency and performance
Oxygen sensors may be covered under emissions warranty. Check with your vehicle manufacturer.
Oxygen sensor-related codes have been common since the introduction of OBD-II systems in vehicles.
Moderate – While the car may still run, ignoring this issue can lead to increased emissions and fuel consumption.
Operating a vehicle with a faulty oxygen sensor can lead to higher emissions, which may not comply with local environmental regulations.
• Ensure the engine is at operating temperature
• Perform tests during deceleration
The oxygen sensor is located in the exhaust system, downstream of the catalytic converter on Bank 2.
Q: What does Bank 2 mean?
A: Bank 2 refers to the side of the engine that does not contain cylinder 1.
Q: Can I drive with a P239F code?
A: While you can drive with this code, it's not recommended as it can lead to poor fuel economy and increased emissions.
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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.
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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.