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 noticed a problem with how hot the special part that helps clean the air (called the ozone reduction catalyst) is compared to the engine's coolant. It's like if your oven and your fridge were both supposed to be at the same temperature, but one was too hot or too cold.
The P143C code is triggered when there is an unexpected difference between the temperature of the direct ozone reduction catalyst and the radiator coolant temperature. This can indicate an issue with the temperature sensors or the cooling system.
The direct ozone reduction catalyst is part of the vehicle's emissions control system. It reduces ozone emissions by converting them into less harmful substances. The vehicle's engine control module (ECM) monitors the temperature of this catalyst and compares it with the radiator coolant temperature to ensure proper operation. A discrepancy between these temperatures can indicate a malfunction in the system.
• Check Engine Light (CEL) is on
• Poor fuel efficiency
• Increased emissions
• Faulty temperature sensor
• Cooling system malfunction
• Wiring issues or poor connections
Catalyst: A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
ECM: Engine Control Module, the brain of the car that controls the engine's operations.
• Use an OBD-II scanner to confirm the code.
• Inspect temperature sensors for damage or malfunction.
• Check wiring and connections for faults.
• Replace faulty temperature sensor.
• Repair or replace damaged wiring.
• Inspect and repair cooling system components.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Toyota Prius
• Lexus CT200h
• Honda Insight
• Regular maintenance of cooling system
• Periodic inspection of sensors
• Ensure proper electrical connections
Sensor Issue
• Get the vehicle checked by a professional mechanic.
• Avoid driving long distances until the issue is resolved.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with hybrid vehicles that utilize advanced emissions control systems.
Moderate – It should be addressed soon to prevent potential damage to the emissions system.
Ignoring emissions-related issues can lead to increased pollution and may fail emissions testing required by law.
• Engine at operating temperature
• Vehicle running at idle
The direct ozone reduction catalyst is located in the exhaust system near the catalytic converter.
Q: Can I drive with a P143C code?
A: It's not recommended to drive for long distances with this code active, as it could lead to increased emissions and potential damage to the vehicle's emissions system.
Q: How can I reset the P143C code?
A: You can reset the code using an OBD-II scanner, but it's important to fix the underlying issue first to prevent the code from returning.
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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.
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Fitment Required · Vehicle-fitment part
Relevant when coolant-temperature and warm-up faults indicate a thermostat-related issue.
Coolant-temperature and warm-up faults often lead to thermostat testing and replacement.
Thermostats are vehicle-specific and should be matched by engine and housing style.
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.