P042C - OBD Trouble Code

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A number of temperature sensors are used by the catalytic converter to ensure that the catalytic converter does not overheat and is working efficiently. If an incorrect signal is determined from the catalytic converter temperature sensor by the engine control module, then the powertrain control module would start flashing the P042C trouble code.

The fault code P042C can be described as Catalyst Temperature Sensor Circuit Low Bank 1 Sensor 2. P042C code is set when the PCM would detect a range of performance problem in bank 1, catalyst temperature sensor 2 circuit.

What causes this problem with the Catalyst Temperature Sensor Circuit Low Bank 1 Sensor 2?

• Exhaust air/fuel mixture might be out of balance
• Catalyst Temperature Sensor circuit might have bad electrical connection
• There can be some faults in the oxygen sensor
• Issues related to wiring
• The catalyst temperature sensor might have some defects
• The PCM/PCM programming can be defective
• There can be opened or shorted catalyst temperature sensor harness

1. Air Fuel Ratio Sensor - Do you remember when was the last time you got your car Air Fuel Ratio Sensor checked up? A faulty Air Fuel Ratio Sensor can cause a lot of issues like displaying P042C code.
2. Oxygen Sensor - Are there some faults in your Oxygen Sensor? Don’t waste time and get them replaced or else P042C code can turn up.
3. Diagnostic Tool - Thinking of buying new Car Diagnostic Tools? You can always rely on us as we have best Automotive Diagnostic Tools for our customers.
4. Catalytic Converter - Everything is fine with Oxygen Sensor and still P042C code triggering? Then you must get your Catalytic Converter checked.
5. Engine Control Module - There can be some issues with the Engine Control Module due to which you may see P042C code appearing over and over again. Visit us to buy best quality Engine Control Module online.
6. Powertrain Control Module - A lot of issues can arise do to defective Powertrain Control Module. Did you just see P042C code flashing? Now you know the reason why it is appearing. Get it inspected and replaced on time.
7. Exhaust System Parts - Faulty Exhaust System Parts can be the reason why P042C code is flashing. Visit us to purchase top notch Exhaust System Parts online.

Our main motive is to achieve customer satisfaction and that’s why we will help you to diagnose P042C code by mentioning some major symptoms below:

Common Symptoms

• The engine performance might be bad
• Decrease in the overall fuel economy
• The check engine light can start flashing
• The emissions can start rising

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P042C:

• The programming error in the PCM can cause a lot of issues, so it would be better to get it restored
• Repair the defaults in the wiring
• Make sure that the electrical connection in the catalyst temperature sensor circuit is checked and you can always correct it as per the need
• Replace the faulty catalyst temperature sensor

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Here are some steps which you should follow in order to diagnose this fault code:

Start your diagnosis by visually inspecting the downstream oxygen sensor and the corresponding wiring. Look for loose connections, damaged wiring, etc. You should also inspect for exhaust leaks both visually as well as audibly. A false oxygen sensor code can be cause due to an exhaust leak. If damage is found, repair as necessary, clear the code and see if it returns.

The next step would be to check for technical service bulletins regarding the issue. If nothing is found, you will need to move forward to step by step diagnosis of the system. The following is a generalized procedure, as testing for this code varies between vehicles. To accurately test the system, you can always refer to a vehicle make/model specific diagnostic flow chart.

Check for other DTCs

• Oxygen sensor codes can often be set because of engine performance problems that cause an out of balance air/fuel mixture.
• If there are other DTCs stored, you can always address those first before proceeding with oxygen sensor diagnosis.

Check Sensor Operation

• You can always use a scan tool, or an oscilloscope. Since most individuals don't have access to a scope, so we will cover oxygen sensor diagnosis using a scan tool.
• Connect the scan tool to the OBD port under the dash. Turn the scan tool on and choose the Bank 1 Sensor 2 voltage parameter from the data list.
• Bring the engine up to operating temperature and view the sensor operation on the scan tool in graph mode.
• The sensor should have a steady 0.45 volt reading with only very small fluctuations. If it is not responding correctly then it should be replaced.

Check the circuit

• Oxygen sensors produce their own voltage signal which is sent back to the PCM. Before proceeding, you can always consult the factory wiring diagrams to determine which wires are which. To check for continuity between the sensor and PCM, turn the ignition key to the "off" position and disconnect the O2 sensor connector.
• Connect a digital multimeter set to ohms with the ignition off between the O2 sensor signal terminal on the PCM and the signal wire. If the meter reads out of limits (OL) there is an open circuit between the PCM and sensor that will need to be located and repaired. If the meter reads a numeric value, it means that there is continuity.
• Next, you'll want to check the ground side of the circuit. To do this, turn the ignition key to the "off" position and disconnect the O2 sensor connector. Connect a digital multimeter set to ohms (with the ignition off) between the O2 sensor connector ground terminal (harness side) and chassis ground.
• If the meter reads out of limits (OL) there is an open circuit on the ground side of the circuit that will need to be located and repaired. If the meter reads a numeric value, there is continuity to ground.
• Finally, you should check that the PCM is processing the O2 sensor signal properly. To do this, leave all the connectors attached and insert a back-probe meter lead into the signal terminal at the PCM. Set the digital multimeter to the DC volts setting.
• With the engine warmed up, compare voltage reading on the meter to that on the scan tool. If the two do no match, the PCM is likely faulty and there is a need to reprogram the powertrain control module.

Common Mistakes When Diagnosing The P042C Code

• Defects in the catalytic converter temperature sensor
• Failure in the powertrain control module
• Wiring issue