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 has detected a problem with the voltage going to a sensor that measures ammonia levels in the exhaust. It's like when a toy needs a specific battery, but the battery is too strong and might break it.
The P24EC code indicates that the voltage supplied to the NH3 (ammonia) sensor is higher than the expected range.
The NH3 sensor is part of the vehicle's emission control system, specifically used in vehicles with Selective Catalytic Reduction (SCR) to monitor ammonia levels in the exhaust. A high voltage circuit issue suggests that there might be an electrical fault, such as a short circuit or a problem with the power supply to the sensor.
• Check Engine Light is on
• Possible decrease in fuel efficiency
• Potential increase in emissions
• Faulty NH3 sensor
• Wiring issues such as short circuits
• Defective power supply or control module
NH3: Ammonia
SCR: Selective Catalytic Reduction
• Use an OBD-II scanner to confirm the code
• Inspect the NH3 sensor and its wiring for damage or disconnection
• Check the voltage supply to the sensor
• Replace the NH3 sensor if faulty
• Repair or replace damaged wiring
• Check and replace any faulty control modules
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regularly inspect and maintain the emission control system
• Ensure proper connections and wiring integrity
• Use recommended fuel and additives
Sensor Issue
• Avoid driving for extended periods with the Check Engine Light on
• Consult a professional mechanic for a thorough inspection
Check with your vehicle's manufacturer for warranty coverage on emission control components.
This code has become more common with the increased use of SCR systems in diesel vehicles to meet emission standards.
Moderate – While the vehicle may still be drivable, it is important to address this issue to ensure compliance with emissions standards and avoid potential damage.
Driving with emission-related issues may violate environmental regulations and can lead to fines or penalties.
• Engine running at operating temperature
• Vehicle in closed-loop operation
The NH3 sensor is typically located in the exhaust system, near the SCR catalyst.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to increased emissions and potential damage to the emission control system.
Q: Can I fix this myself?
A: If you have experience with automotive electrical systems, you might be able to diagnose and fix wiring issues. Otherwise, it's best to consult a professional.
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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.