Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the sensor that checks the amount of ammonia in the car's exhaust. Ammonia is used to help clean up the exhaust gases.
The P24E1 code indicates an issue with the ammonia (NH3) sensor circuit, which is responsible for monitoring the ammonia levels in the exhaust system.
The NH3 sensor is part of the vehicle's emissions control system and is used to measure the amount of ammonia in the exhaust gases. This sensor helps ensure that the vehicle meets emissions standards by monitoring the effectiveness of the Selective Catalytic Reduction (SCR) system. A fault in the sensor circuit can lead to incorrect readings and potentially increased emissions.
• Check Engine Light (CEL) is on
• Poor fuel economy
• Failed emissions test
• Faulty NH3 sensor
• Damaged wiring or connections in the sensor circuit
• ECU malfunction
NH3: Ammonia, a compound used in emissions control systems
SCR: Selective Catalytic Reduction, a system that reduces emissions by injecting a urea solution into the exhaust
• Use an OBD-II scanner to confirm the code
• Inspect the NH3 sensor and its wiring for damage
• Test the sensor's voltage and resistance
• Replace the NH3 sensor if faulty
• Repair or replace damaged wiring or connectors
• Reprogram or replace the ECU if necessary
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Volkswagen Jetta
• BMW 3 Series
• Audi A4
• Regularly maintain the emissions control system
• Inspect wiring and connections periodically
• Use quality fuel to prevent sensor contamination
Sensor Issue
• Address the issue promptly to avoid increased emissions
• Consult with a professional mechanic if unsure about repairs
Check with the vehicle manufacturer for emissions-related warranty coverage.
This code has become more common with the increased use of SCR systems in modern vehicles to meet stringent emissions standards.
Moderate – While the vehicle may still run, emissions and fuel efficiency may be affected.
Driving with a faulty emissions sensor may lead to failing emissions tests and potential fines.
• Engine at operating temperature
• Vehicle in closed-loop mode
The NH3 sensor is typically located in the exhaust system, near the SCR catalyst.
Q: What does the NH3 sensor do?
A: It measures the level of ammonia in the exhaust gases to ensure the emissions system is working properly.
Q: Can I drive with a P24E1 code?
A: It's possible, but it's not recommended as it may affect emissions and fuel efficiency.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
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.
View on Amazon
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.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
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.