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 isn't getting a signal from a sensor that checks for pollution gases when the car starts. It's like trying to watch TV without a signal.
The NOx sensor is responsible for measuring the levels of nitrogen oxides in the exhaust gases. This code indicates that the sensor's signal is not being detected by the engine control module (ECM) during startup.
The P124E code is triggered when the ECM does not receive a signal from the NOx sensor on Bank 2 during the initial startup of the vehicle. This could be due to a faulty sensor, wiring issues, or a problem with the ECM itself.
• Check Engine Light is on
• Increased emissions
• Possible reduction in engine performance
• Faulty NOx sensor
• Damaged wiring or connectors
• Faulty ECM
NOx: Nitrogen Oxides, harmful pollutants produced during combustion.
ECM: Engine Control Module, the computer that controls engine functions.
• Check for any other related codes and address them first.
• Inspect the wiring and connectors for damage or corrosion.
• Test the NOx sensor for proper operation.
• Replace the faulty NOx sensor.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $600
Moderate
• Ford F-150
• Chevrolet Silverado
• Dodge Ram 1500
• Regular maintenance of the exhaust system.
• Ensure proper fuel quality.
• Regularly inspect sensors and wiring.
Sensor Issue
• Have the vehicle inspected by a professional if the Check Engine Light comes on.
• Avoid driving the vehicle excessively until the issue is resolved.
Check with your vehicle manufacturer for warranty coverage on emission-related components.
This code has become more common with the increased use of NOx sensors in modern vehicles to meet emission standards.
Moderate – While the vehicle may still be drivable, it could lead to increased emissions and potential damage to the catalytic converter.
Driving with a malfunctioning NOx sensor may lead to higher emissions, which could violate environmental regulations.
• Vehicle must be started from a cold state.
• Ensure all electrical connections are secure.
The NOx sensor for Bank 2 is typically located on the exhaust system, downstream of the catalytic converter on the side of the engine with cylinder 2.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to increased emissions and potential damage to the catalytic converter.
Q: Can I drive with the P124E code?
A: While the vehicle may still be drivable, it's recommended to address the issue to avoid further damage and increased emissions.
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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.