Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car has a sensor that checks how much pollution it's making. This sensor has a problem because its wires are touching each other, which is not good.
The P122C code indicates that the NOx sensor, which measures nitrogen oxide levels in the exhaust, has a short circuit in its wiring on Bank 1.
The NOx sensor is responsible for monitoring the levels of nitrogen oxides in the exhaust gases. When the Engine Control Module (ECM) detects a short circuit in the sensor's wiring, it triggers the P122C code. This can affect the vehicle's emission control system and overall performance.
• Check Engine Light is on
• Reduced engine performance
• Increased emissions
• Damaged NOx sensor wiring
• Faulty NOx sensor
• Corroded or loose connectors
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 NOx sensor wiring for damage or shorts.
• Check the connectors for corrosion or looseness.
• Repair or replace damaged wiring.
• Replace the NOx sensor if faulty.
• Clean and secure all connectors.
• OBD-II scanner
• Multimeter
• Socket set
$200 - $500
Moderate
• Volkswagen Passat
• Audi A4
• BMW 3 Series
• Regularly inspect sensor wiring.
• Ensure connectors are secure.
• Keep the engine bay clean to prevent corrosion.
Sensor Issue
• Address the issue promptly to avoid further damage.
• Consult a professional mechanic if unsure about repairs.
Check with the vehicle manufacturer for sensor-related warranty coverage.
This code has been associated with vehicles using advanced emission control systems to meet stringent regulations.
Moderate – While the car may still run, emissions and performance could be affected.
Driving with a malfunctioning NOx sensor can lead to increased emissions, which may violate environmental regulations.
• Engine at operating temperature
• Vehicle in a well-ventilated area
The NOx sensor is typically located in the exhaust system, upstream of the catalytic converter on Bank 1.
Q: What does Bank 1 mean?
A: Bank 1 refers to the side of the engine with cylinder 1.
Q: Can I drive with a P122C code?
A: It's not recommended as it can affect emissions and engine performance.
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Useful when diagnosis points toward damaged wiring, corroded terminals, or connector 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.