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 reading the sensor that checks for pollution gases from the engine. It's like when a thermometer can't tell if it's hot or cold outside.
The NOx sensor is responsible for measuring nitrogen oxide levels in the exhaust gases. When the sensor's readings are out of the expected range, this code is triggered.
P23AD indicates an issue with the NOx sensor circuit for Bank 1 Sensor 3. This could be due to a malfunction in the sensor itself, wiring problems, or issues with the engine control module (ECM) that processes the sensor data.
• Check Engine Light is on
• Poor fuel economy
• Reduced engine performance
• Faulty NOx sensor
• Wiring issues or poor connections
• Malfunctioning engine control module (ECM)
NOx: Nitrogen Oxides, pollutants produced during combustion.
ECM: Engine Control Module, the computer that controls 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.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Socket set
$200 - $600
Moderate
• Volkswagen Jetta
• Audi A3
• BMW 3 Series
• Regular maintenance and inspection of sensors.
• Ensure proper fuel quality.
• Check and clean exhaust components regularly.
Sensor Issue
• Have the vehicle diagnosed by a professional.
• Avoid driving long distances until the issue is resolved.
Check with the vehicle manufacturer for warranty coverage on emissions components.
This code has been more prevalent in diesel vehicles due to their complex emissions systems.
Moderate – It's advisable to address this issue soon to avoid potential damage to the emissions system.
Driving with a malfunctioning emissions sensor may not be legal in some areas due to pollution regulations.
• Engine at operating temperature
• Vehicle in closed-loop mode
The NOx sensor is typically located in the exhaust system, near the catalytic converter.
Q: Can I drive with a P23AD code?
A: It's not recommended to drive for long periods with this code, as it can affect emissions and engine performance.
Q: How do I clear a P23AD code?
A: After repairs, the code can be cleared with an OBD-II scanner. However, ensure the issue is fixed first.
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Universal · Digital multimeter
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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.