Fault code P046A – catalyst temperature sensor 1/2 correlation (Bank 1)

Fault code P046A is called “Catalyst Temperature Sensor 1/2 Correlation (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 P046A

This diagnostic trouble code (DTC) is a generic code. Error P046A is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

The catalytic converter is a part of the exhaust system that looks like a muffler. But its operation is very different from that of a muffler. The catalytic converter works by reducing exhaust emissions.

Temperature sensors are installed on the catalytic converter in some models. When the vehicle is warmed up and running in closed loop mode. The temperature sensor readings should fluctuate, since the temperature cannot be constant all the time. If the readings from the sensors start to vary greatly from the reference, the control module makes adjustments.

Usually code P046A is set and the check engine light (Check Engine) comes on. If the Powertrain Control Module (PCM) detects a discrepancy between the catalytic converter temperature sensor signals. The error indicates that there is a malfunction in the catalyst reading and the catalyst is not operating as efficiently as it should (per specifications).

The first and second sensors can also be called the temperature sensors before and after the catalyst, respectively. They are usually placed just before and just after the catalytic converter in the exhaust system.

When the engine is running and sufficiently warmed up, the exhaust gases entering the catalytic converter. Should be noticeably cooler than the exhaust gases exiting the converter.

The PCM constantly monitors the catalyst temperature sensors and compares their signals. If the degree of deviation between them is not within the programmed value. Code P046A will be stored, and the Malfunction Indicator Light (MIL) may illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P046A 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 emission of harmful substances in the exhaust gases.
4. Black smoke coming from the exhaust pipe.
5. Increased fuel consumption.
6. Sometimes there may be no symptoms, despite a stored fault code.

This error is considered moderate if there are no symptoms. But if symptoms are present, the cause of error P046A should be corrected as soon as possible. Ignoring it may cause serious damage to the catalytic converter.

Factors that can cause this error code

The error code P046A can mean that one or more of the following problems have occurred:

• Exhaust temperature sensor is defective.
• Damaged or incorrectly connected wiring.
• Short circuit in the exhaust temperature sensor circuit.
• Catalytic converter has failed.
• Sometimes the cause is a defective PCM module.

How to fix or reset OBD-2 code P046A

Some suggested steps for troubleshooting and fix the error code P046A:

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 sensor.
3. Diagnose any other error codes that may have caused code P046A.
4. Check the wires and connections for wear and damage.
5. Test-drive the vehicle to check the oxygen sensor.
6. Replace or reprogram the faulty PCM if necessary.

Diagnose and repair of problems

If there are no additional errors, clear fault code P046A 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 oxygen sensor. Sometimes the electrical connector may disconnect due to heat and vibration, and the engine error indicator light will come on.

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

Read the inlet temperature reading of the transducer and then the outlet temperature reading. The difference between the input and output temperatures should be about 100°F. If the temperature difference approaches 200°F or reaches 500°F. Most likely the catalytic converter is damaged.

Test the temperature sensor, inspect the wires

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

Check the operation of the temperature 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 temperature oxygen sensors will most likely fix the error. But sometimes, you need to replace the catalytic converter to fix the problem. If code P046A is combined with other codes, try fixing the other codes first.

On which vehicles does this problem occur most frequently

Fault code P046A can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

• Chevrolet
• Dodge (RAM)
• Ford
• Skoda
• Volkswagen

Fault code P046A can sometimes be found with other errors. The most common are the following: P0425, P0426, P0427, P0428, P0429, P046B.

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