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 remembering how to measure a special gas called ammonia (NH3) in the exhaust. It's like when you forget how to use a calculator to solve a math problem.
The P24ED code indicates an issue with the calibration memory of the NH3 sensor, which is responsible for measuring ammonia levels in the vehicle's exhaust system.
The NH3 sensor is part of the vehicle's emission control system. It measures ammonia levels to ensure the catalytic converter is working properly. The calibration memory stores data that helps the sensor accurately measure ammonia. If there's a problem with this memory, the sensor might not work correctly, leading to inaccurate emissions readings.
• Check Engine Light is on
• Failed emissions test
• Possible decrease in fuel efficiency
• Faulty NH3 sensor
• Corrupted calibration data
• Wiring or connector issues
NH3: Ammonia, a compound of nitrogen and hydrogen used in emissions control.
Calibration Memory: Data stored in a sensor's memory to help it measure accurately.
• Use an OBD-II scanner to confirm the P24ED code.
• Inspect the NH3 sensor and its wiring for damage.
• Check the calibration data for corruption.
• Replace the NH3 sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Reprogram or reset the calibration memory.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Toyota Prius
• Honda Accord Hybrid
• Chevrolet Volt
• Regular maintenance checks
• Timely replacement of sensors
• Ensure proper vehicle software updates
Sensor Issue
• Get the vehicle checked by a professional mechanic.
• Avoid ignoring the Check Engine Light as it may lead to more severe issues.
Check with the vehicle manufacturer for warranty coverage on emission-related components.
This code has become more common with the increased use of advanced emission control systems in modern vehicles.
Moderate – Addressing this issue promptly can prevent further emissions problems.
Driving with a faulty emission system can lead to fines and increased environmental pollution.
• Vehicle at operating temperature
• Stable idle conditions
The NH3 sensor is typically located in the exhaust system, near the catalytic converter.
Q: Can I drive with a P24ED code?
A: While the car may still run, it's best to address this issue to avoid potential emissions problems and ensure compliance with regulations.
Q: How do I know if the NH3 sensor is faulty?
A: A professional mechanic can test the sensor using diagnostic tools to determine if it's working correctly.
Budget · Enhanced code reader
A wired color-screen reader with readiness hotkeys, live data, code definitions, and data logging.
Good for emissions-related codes because it exposes readiness monitors and live powertrain data.
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Specialty · Smoke machine
Helpful for finding EVAP and vacuum leaks that are hard to see with visual inspection alone.
Helpful for tracking down EVAP and vacuum leaks that can trigger emissions faults.
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Specialty · O2 sensor socket
Helpful when the code points toward exhaust or oxygen-sensor work and space is tight.
Useful when the diagnosis points toward oxygen-sensor removal or replacement.
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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.