Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer found a problem with a sensor that checks pollution levels. It's like a broken thermometer that can't tell you the right temperature.
The NOx sensor on Bank 2 is reporting a short circuit, meaning the electrical signals are not being transmitted properly.
The NOx (Nitrogen Oxide) sensor is used to measure the levels of nitrogen oxides in the exhaust gases. A short circuit in the sensor's circuit means there is an unintended path for the electrical current, which can cause incorrect readings or no readings at all.
• Check Engine Light is on
• Poor fuel economy
• Decreased engine performance
• Damaged NOx sensor
• Faulty wiring or connectors
• Corrosion in the sensor circuit
NOx: Nitrogen Oxides, pollutants produced during combustion
Bank 2: The side of the engine that does not contain cylinder 1
• Use an OBD-II scanner to confirm the code
• Inspect the NOx sensor and wiring for damage
• Test the sensor circuit for continuity and shorts
• Replace the NOx sensor
• Repair or replace damaged wiring
• Clean corroded connectors
• OBD-II scanner
• Multimeter
• Socket set
$200 - $500
Moderate
• BMW 3 Series
• Ford F-150
• Volkswagen Passat
• Regularly inspect exhaust system components
• Ensure proper maintenance of the vehicle
• Use high-quality fuel
Sensor Issue
• Avoid driving long distances until repaired
• Consult a professional mechanic
• Check for any recalls related to the NOx sensor
Check if the sensor is covered under the vehicle's emissions warranty.
This code has been associated with vehicles that have high mileage and are exposed to harsh environmental conditions.
Moderate – Should be addressed soon to prevent further engine issues.
Driving with a faulty NOx sensor can lead to increased emissions, which may not comply with local environmental regulations.
• Engine at operating temperature
• Vehicle driven under normal conditions
The NOx sensor is typically located in the exhaust system, downstream of the catalytic converter on Bank 2.
Q: Can I drive with a P122D code?
A: It's possible, but not recommended as it can lead to further engine issues and increased emissions.
Q: How often should the NOx sensor be replaced?
A: NOx sensors typically last around 100,000 miles, but this can vary based on driving conditions and vehicle maintenance.
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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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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.