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 is having trouble remembering the settings for a special sensor that checks the air coming out of the engine. It's like when you forget where you put your favorite toy.
The P225B code indicates an issue with the calibration memory of the NOx sensor located in Bank 1, Sensor 2. This sensor helps monitor and control the emissions of nitrogen oxides from the vehicle.
The NOx sensor is responsible for measuring the levels of nitrogen oxides in the exhaust gases. The calibration memory stores specific data required for the sensor to function correctly. If the calibration memory is lost or corrupted, the sensor cannot accurately measure NOx levels, leading to this error code.
• Check Engine Light is on
• Reduced fuel efficiency
• Failed emissions test
• Faulty NOx sensor
• Corrupted calibration data
• Wiring issues or poor connections
NOx: Nitrogen Oxides, pollutants produced during combustion.
ECM: Engine Control Module, the computer that manages engine functions.
• Use an OBD-II scanner to confirm the code.
• Inspect the NOx sensor and its wiring for damage.
• Check for any software updates or reprogramming needs.
• Replace the faulty NOx sensor.
• Reprogram the engine control module (ECM) if necessary.
• Repair or replace damaged wiring or connectors.
• OBD-II scanner
• Digital multimeter
• Socket set
$200 - $600
Moderate
• Toyota Camry
• Ford F-150
• BMW 3 Series
• Regular maintenance checks
• Ensure wiring and connectors are secure
• Update vehicle software as recommended
Sensor Issue
• Take your car to a professional for diagnosis and repair.
• Avoid driving long distances until the issue is resolved.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code has become more common with the introduction of stricter emissions standards and the increased use of NOx sensors.
Moderate – Address the issue soon to avoid potential emissions violations and maintain fuel efficiency.
Driving with a malfunctioning NOx sensor may lead to increased emissions, which could be illegal in some areas.
• Engine running at normal operating temperature
• Vehicle driven under varied load conditions
The NOx sensor is typically located in the exhaust system, downstream of the catalytic converter on Bank 1.
Q: What does a NOx sensor do?
A: A NOx sensor measures the amount of nitrogen oxides in the exhaust gases to help control emissions.
Q: Can I drive with a P225B code?
A: While the car may still be drivable, it's best to address the issue soon to avoid increased emissions and potential damage.
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Universal · Digital multimeter
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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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.