Fault code P2423 – hydrocarbon adsorption catalyst efficiency below threshold (Bank 1)

Fault code P2423 is called “Hydrocarbon (HC) Adsorption Catalyst Efficiency Below Threshold (Bank 1)” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P2423

Code P2423 in a vehicle with internal combustion engine means that the transmission control module has detected a hydrocarbon adsorption catalyst efficiency below the threshold value. This error refers to Bank 1. Bank 1, is the engine group in which cylinder number 1 is located.

The hydrocarbon absorbing catalyst (HCAC) system includes a three-component catalyst and two heated oxygen sensors. The three-component catalyst absorbs hydrocarbons released shortly after the engine is started.

If this code appears, Bank 1 signals that its hydrocarbon adsorption and catalyst efficiency is below the acceptable threshold.

The engine control module (ECM) receives information. This includes the composition of the exhaust gases as well as the temperature from the vehicle’s oxygen sensors. It then determines the degree of catalytic converter efficiency required.

If the PCM detects that the efficiency of the adsorption hydrocarbon catalyst is not sufficient for the minimum allowable parameters. Then code P2423 will be stored and the malfunction indicator light may illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P2423 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
2. Other related fault codes may also be present.
3. Increased emissions of harmful substances in the exhaust gases.
4. Increased fuel consumption.
5. Reduced engine power output.
6. Excessive black smoke from the vehicle’s tailpipe.
7. Sometimes there may be no symptoms, despite a stored fault code.

Any stored codes related to the SCR Selective Catalyst Recovery System can initiate a shutdown of that system. Stored code P2423 should be considered serious and corrected as soon as possible. If the code is not corrected, it may cause damage to the catalytic converter.

Factors that can cause this error code

The error code P2423 can mean that one or more of the following problems have occurred:

• Damaged or faulty exhaust temperature sensor.
• Damaged or incorrectly wired exhaust gas temperature sensor.
• Faulty hydrocarbon adsorption catalyst system.
• Exhaust leaks in front of the catalytic converter.
• Installation of non-original or high-performance exhaust system components.
• Sometimes the cause is a faulty PCM module or its programming error.

How to fix or reset OBD-2 code P2423

Some suggested steps for troubleshooting and fix the error code P2423:

1. Read all error codes stored in the vehicle’s PCM memory with an OBD-II scan tool.
2. Check the operation of the exhaust temperature oxygen sensor.
3. Diagnose other error codes that may have caused code P2423.
4. Repair any emission leaks.
5. Test-drive the vehicle to check the operation of the exhaust temperature sensor.
6. Replace or reprogram faulty PCM if necessary.

Diagnose and repair of problems

If there are no additional errors, clear fault code P2423 and perform a short test drive. To allow the PCM to go into closed loop mode, then scan the system again and see if the code comes back.

Check the catalytic converter and leaks

Check for exhaust leaks, repair them if necessary. Inspect any electrical connections that are connected to the exhaust temperature sensor. Sometimes heat and vibration can cause the electrical connector to disconnect and the engine error indicator light will come on.

If a code is found, check the operation of the sensor to make sure it is working properly. Compare the displayed output signals with the values indicated in the manual.

Test temperature sensor, inspect wiring

Check the wiring harness that goes to the exhaust temperature sensor. It is important to make sure that there are no burned out, broken or severely loose spots. Which could hit any moving component while the car is in motion.

Check the operation of the sensor by thoroughly warming up the engine. Remember that the sensor will only work once it has reached its operating temperature.

Connect the sensor output to a multimeter and run the engine at about 2000-2500 rpm. The output should show a voltage fluctuating between 0.1 and 0.9 V. If the sensor output does not change or the response time is too long. This means you have a bad sensor, you should replace it.

Replacing the sensor will most likely correct the error. But sometimes, you need to replace the catalytic converter to fix the problem. If code P2423 is combined with other codes, try fixing the other codes first.

On which vehicles does this problem occur most frequently

Fault code P2423 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

• Mitsubishi (Lancer)
• Nissan (Altima, Rogue)
• Toyota (Camry)

Fault code P2423 can sometimes be found with other errors. The most common are the following: P2424, P20EC, P20ED, P20EE, P20EF.

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