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 sensor in the car that checks for pollution is not working fast enough. It's like if you asked someone a question and they took too long to answer.
The NOx sensor is responsible for measuring nitrogen oxide levels in the exhaust. This code indicates that the sensor is taking too long to detect changes from high to low levels of NOx in the exhaust gas.
The P23C2 code is triggered when the Engine Control Module (ECM) detects that the response time of the NOx sensor, specifically Bank 1 Sensor 3, is slower than expected when transitioning from high to low NOx levels. This can affect the vehicle's emissions performance.
• Check Engine Light illuminated
• Possible decrease in fuel efficiency
• Failed emissions test
• Faulty NOx sensor
• Wiring or connection issues to the NOx sensor
• Exhaust leaks affecting sensor readings
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 wiring and connections to the NOx sensor
• Test the NOx sensor for proper operation
• Replace the NOx sensor if faulty
• Repair or replace damaged wiring or connectors
• Fix any exhaust leaks
• OBD-II scanner
• Multimeter
• Wrench set
$200 - $600
Moderate
• Volkswagen Passat
• Audi A4
• BMW 3 Series
• Regularly inspect and maintain the exhaust system
• Ensure timely replacement of sensors
• Keep the vehicle's software updated
Sensor Issue
• Get the vehicle checked by a professional mechanic
• Avoid ignoring the Check Engine Light
• Consider regular maintenance to prevent future issues
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code has become more common with the increased use of NOx sensors in modern vehicles to meet stricter emissions standards.
Moderate – It should be addressed soon to avoid potential emissions test failures.
Driving with a faulty NOx sensor may result in increased emissions, which is illegal in some regions and can lead to fines.
• Vehicle at operating temperature
• Steady driving conditions
The NOx sensor is typically located in the exhaust system, downstream of the catalytic converter.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to increased emissions and potential failure of emissions tests.
Q: Can I drive my car with this code?
A: While the car may still be drivable, it's best to address the issue to avoid emissions problems.
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Network faults often require full-system access instead of a generic code reader alone.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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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.