P0428 - OBD Trouble Code

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The error code P0428 can be defined as Catalyst Temperature Sensor High (Bank 1). 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 P0428 trouble code.

One of the most important pieces of emissions equipment on a vehicle is the catalytic converter. There are some exhaust gases which would pass through the catalytic converter which would then give rise to a chemical reaction. When this reaction has taken place, it would convert carbon monoxide, nitrogen oxides and hydrocarbon into harmless water as well as carbon dioxide.

Two oxygen sensors would then monitor the converter efficiency, one which is mounted upstream from the converter and the other one is mounted downstream. After comparing the oxygen sensor signals, then PCM can easily determine if the catalytic converter is working efficiently.

What causes this problem with the Catalyst Temperature Sensor High (Bank 1)?

• Defaults in the oxygen sensor
• The PCM/PCM programming might be quirky
• Catalyst temperature sensor harness might be opened or shorted
• There can be poor electrical connection in the catalyst temperature sensor circuit
• Flaws in the catalyst temperature sensor
• Problems related to wiring
• The exhaust air/fuel mixture can be out of balance

1. Oxygen Sensor - Did your mechanic just found out that there is some fault in the Oxygen Sensor? Buy top notch Denso Oxygen Sensor from us at economical prices.
2. Powertrain Control Module - A broken Powertrain Control Module can cause a lot of issues. It would be nice if you get it replaced on time.
3. Exhaust System Parts - Everything is fine with the engine control module and still OBD code P0428 flashing? Then there is definitely some fault with the Exhaust System Parts. Get them checked and replace if needed.
4. Catalytic Converter - Catalytic Converter is an important car part which should never be neglected. May be there is some fault in it due to which P0428 code may start flashing.
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6. Air Fuel Ratio Sensor - P0428 code does not really end up spoiling your Catalytic Converter, but it might also accompany few Air Fuel Ratio Sensor issues. We have best Air Fuel Ratio Sensor with us.
7. Engine Control Module - Are you facing OBD Error Code P0428? Don’t worry as you can fix this issue with new Engine Control Module. We care for our customers, that’s why we have Engine Control Module for every make and model.

We care for our customers and that’s why we can totally understand your problem. That’s the reason why we have listed out some major symptoms behind the flashing up of OBD Code P0428. They are mentioned here as follows:

Common Symptoms

• Diminishing fuel economy
• There can be poor engine performance
• Increase in the overall emissions
• Illumination in the check engine light

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 P0428:

• Restore the quirky catalyst temperature sensor
• Wiring should be repaired or replaced properly
• A lot of problems can be caused due to programming error in the PCM, so you can always replace it
• Carefully check the electrical connection in the catalyst temperature sensor circuit

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

• If you want to diagnose the P0428 trouble code, then you should visually inspect 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

• This is best done using a scan tool, or better yet, 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 P0428 Code

• There can be some faults in the catalytic converter temperature sensor
• Powertrain control module might start failing
• Some faults in the wiring