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 talking to a sensor that checks how much pollution is coming out of the car. It's like when your phone can't connect to the internet.
The P122E code indicates an issue with the communication or signal from the NOx sensor, specifically related to the binary oxygen sensor signal circuit being open or not functioning properly.
The NOx sensor is responsible for measuring the levels of nitrogen oxides in the vehicle's exhaust gases. An open circuit or faulty signal in the binary oxygen sensor can prevent the engine control module (ECM) from receiving accurate data, which can affect emission control and engine performance.
• Check Engine Light is on
• Decreased fuel efficiency
• Increased emissions
• Faulty NOx sensor
• Damaged wiring or connectors
• ECM software issue
NOx Sensor: A device that measures the levels of nitrogen oxides in the exhaust gases.
ECM: Engine Control Module, the computer that manages the engine's operation.
• Use an OBD-II scanner to confirm the code.
• Inspect the NOx sensor and its wiring for damage.
• Test the sensor's signal with a multimeter.
• Replace the faulty NOx sensor.
• Repair or replace damaged wiring or connectors.
• Update the ECM software if needed.
• OBD-II scanner
• Multimeter
• Socket set
$200 - $600
Moderate
• Volkswagen Jetta
• Audi A4
• BMW 3 Series
• Regularly inspect and maintain exhaust system components.
• Use high-quality fuel to reduce sensor contamination.
• Ensure regular vehicle servicing to detect issues early.
Sensor Issue
• Avoid driving long distances until the issue is resolved.
• Consult a professional mechanic for accurate diagnosis.
• Do not ignore the Check Engine Light as it may lead to more serious problems.
Check if the vehicle's emissions system is still under warranty, as this may cover sensor replacement.
The P122E code has been increasingly reported in vehicles with advanced emission control systems as manufacturers strive to meet stricter environmental regulations.
Moderate – Addressing this issue promptly can prevent further damage and ensure compliance with emission standards.
Driving with a faulty NOx sensor may result in increased emissions, which can be illegal in some regions and contribute to environmental pollution.
• Engine at operating temperature
• Vehicle idling or at steady speed
The NOx sensor is typically located in the exhaust system, near the catalytic converter.
Q: What happens if I ignore the P122E code?
A: Ignoring this code can lead to decreased fuel efficiency, higher emissions, and potential damage to other engine components.
Q: Can I drive my car with the P122E code?
A: While the car may still be drivable, it's recommended to address the issue to avoid further problems and ensure emission compliance.
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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 the code or supporting diagnostics point toward upstream or downstream oxygen-sensor faults.
This code family often involves upstream or downstream oxygen-sensor diagnosis.
Verify exact sensor position and vehicle fitment before buying.
View options on Amazon
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.