Which Codes Will This Page Cover?
- P0142 O2 Sensor Circuit – Bank 1 Sensor 3
- P0143 O2 Sensor Circuit Low Voltage
- P0144 O2 Sensor Circuit High Voltage
- P0145 O2 Sensor Circuit Slow Response
- P0146 O2 Sensor Circuit no Activity Detected
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What Is the P0142 Code?
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Seriousness
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A P0142 code refers to the issue your vehicle’s Power Control Module (PCM) detects with the oxygen sensor in that it is not operating within a predefined and specified range. The oxygen sensor voltage varies depending on the oxygen content in the exhaust, and if the PCM perceives the signal to be outside of the normal parameters, it will trigger a P0142 code.
The P0142 code itself deals with the oxygen Sensor 3 that lies on the Bank 1 side of the engine or the side of the engine where the #1 cylinder is located. Sensor 3 indicates that the O2 sensor is the third one downstream from the engine. When the PCM thinks this sensor’s voltage is stuck in an abnormal state for a prolonged period or if it’s not responding at all, it will trigger the P0142 code.
More About P0142 And Its Related Codes
As we mentioned, the oxygen sensors measure the amount of oxygen in the exhaust stream, and the PCM uses the signals supplied from the O2 sensors to calculate how much fuel to inject into the combustion chamber of the engine. The PCM uses the signal from the downstream sensors, like Sensor 3, to also determine the efficiency of the catalytic converter. A heater element is also necessary for these oxygen sensors to work and some sensors won’t release a voltage signal until their tip reaches a certain temperature.
The O2 sensors release voltage readings between .1 and .9 usually, and anything that falls outside of these parameters is considered to be abnormal. Therefore, if the PCM senses a low reading (like .2) or a high voltage reading (like 1.3), it will trigger accompanying codes P0143 and P0144, respectively. If it senses a slow response from the O2 sensor, or if it detects no activity at all, it will set the P0145 and P0146 codes, respectively, as well.
What Are the Symptoms of a P0142 Code?
Typically, what you will find first with a P0142 code is that your dash will suddenly be lit with a Check Engine Light. This will be your first indicator that something is possibly wrong and that you should have your vehicle checked out by a qualified technician. The first of the physical symptoms that you can expect with a P0142 or its related codes is that you will have decreased engine performance.
This is because the PCM could be forcing more than normal amounts of fuel into your engine, causing it to “run rich”, or experience lower fuel economy. You can also witness the inverse of this if there isn’t enough fuel being pushed into the motor and your engine stalls when you’re stopped at a red light. You may even notice a rough idle in your car and difficulties accelerating, especially going uphill. This generally can be accompanied by decreased fuel economy and even higher emissions. You will notice this if your exhaust is emitting darker than usual smoke from the tailpipe.
What Are Some Causes of a P0142 Code?
Typically, what you will find first with a P0142 code is that your dash will suddenly be lit with a Check Engine Light. This will be your first indicator that something is possibly wrong and that you should have your vehicle checked out by a qualified technician. The first of the physical symptoms that you can expect with a P0142 or its related codes is that you will have decreased engine performance. This is because the PCM could be forcing more than normal amounts of fuel into your engine, causing it to “run rich”, or experience lower fuel economy. You can also witness the inverse of this if there isn’t enough fuel being pushed into the motor and your engine stalls when you’re stopped at a red light. You may even notice a rough idle in your car and difficulties accelerating, especially going uphill. This generally can be accompanied by decreased fuel economy and even higher emissions. You will notice this if your exhaust is emitting darker than usual smoke from the tailpipe.
How Serious Is the P0142 Code?
While the P0142 code can cause serious issues to engine components if left untreated, it’s still a moderately severe issue that you should have checked out by an experienced technician. The code can contribute to an excessive exhaust emission if the problem is the catalyst, and it will fail emission testing. This will prevent you from legally being able to drive the vehicle on the streets so it should be looked at immediately. If the issue is an exhaust leak, this can cause fumes to get into the passenger compartment, causing potential health hazards. This is why you should drive your car to a service center near you as soon as you’re presented with a P0142 or its related codes.
Can I Still Drive with a P0142 Code?
While the P0142 can initially not present any dramatic symptoms to your car, we still don’t recommend that you drive with the code set. This is because the symptoms can eventually become severe if the issue is left untreated, thus leaving you with much higher repair bills down the road. Your oxygen sensors are vital in the performance of your car, and if the PCM is unable to send the proper amount of fuel consistently to your engine you run the risk of permanently damaging your internal engine parts. Parts like the pistons and valves can eventually succumb to this pressure and break, and this will cause your engine to cease working. This is why we recommend that you take your car to an experienced technician when you see the P0142 code.
How Easy Is It to Diagnose a P0142 Code?
Diagnosing an oxygen sensor circuit malfunction is certainly not a simple task or process, and should be left in the hands of technicians that have experience finding the root cause of these issues. What the technician will do first is check the electrical connections to the O2 sensor on the Bank 1 side and look for any damage to the connectors or the wiring leading from the sensor to the PCM. They will also check the exhaust system before the sensor to check for any leaks that could be causing the PCM to receive faulty voltage readings from the oxygen sensor.
Also, it’s important to note that the engine must be in perfect running condition to properly diagnose a P0142 issue or its related codes. There must be no other misfiring codes present, and there must be no vacuum or exhaust leaks present. That’s why an experienced technician will look to first rule these issues out before proceeding to the sensor or the PCM itself. If there are any air/fuel metering codes present alongside the P0142 code, these codes must be resolved before continuing to the P0142 code itself. This is where a lot of the misdiagnosis comes from and it’s because people will skip these steps and go directly to the P0142 issue first.
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