Oxygen sensors are crucial for engine operation. Their primary function is to measure the oxygen content in the exhaust. However, just like any other engine component, it isn’t uncommon for these sensors to get faulty at one point. Error code P0142 is one of the several diagnostic trouble codes related to a faulty oxygen sensor circuit.
If your scan tool reads this code, it is best to have the issue checked right away. Here is some helpful information about this trouble code.
What Does the P0142 Code Mean?
Diagnostic trouble code (DTC) P0142 stands for “O2 Sensor Circuit (Bank 1 Sensor 3).” It is triggered once the vehicle’s powertrain control module (PCM) perceives that the bank 1, oxygen sensor 3’s voltage is stuck in an abnormal state for a specific period or that it isn’t responding at all.
“Sensor 3” refers to the third downstream oxygen sensor that’s located in bank 1 of the engine.
As mentioned earlier, oxygen sensors measure the amount of oxygen in the exhaust stream. The PCM uses the signal from the upstream oxygen sensors (before the catalytic converter) to calculate how much fuel to inject into the engine.
On the other hand, the module primarily uses the signal from the downstream sensors (after the catalytic converter) to determine the efficiency of the catalytic converter. A heater element is necessary for the oxygen sensor to function as it should. A typical zirconia sensor will not send a voltage signal until its tip reaches a certain temperature.
The oxygen sensor voltage varies depending on the oxygen content in the exhaust. Once the PCM perceives the signal to be outside of the normal operating parameters, it will trigger an oxygen sensor error code. In this case, it will trigger a P0142 code.
Note: The definition of code P0142 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
What are the Possible Causes of the P0142 Code?
Here are the possible triggers of this error code:
- Faulty oxygen sensor (bank 1, sensor 3)
- Exhaust leak
- Possible wiring issue
- An issue with the PCM
What are the Common Symptoms of a P0142 Code?
Here are some of the common symptoms related to a P0142 code:
- Illuminated check engine light
- Decreased engine performance
- Decreased fuel efficiency
- Increase in tailpipe emissions
How to Diagnose the P0142 Code
Diagnosing an oxygen sensor circuit malfunction is difficult. If you’re not familiar with oxygen sensors and their circuitry, it is best to bring your vehicle to an auto repair shop. A professional would know how to properly diagnose the problem.
If you’re an experienced DIYer who wants to try to diagnose this code yourself, check out vehicle-specific repair manuals or online repair databases. These resources contain helpful troubleshooting information, including how to diagnose problems in an oxygen sensor circuit.
How to Fix the P0142 Code
P00142 is a generic trouble code, which means it may appear on various makes and models. However, it doesn’t mean that there is one solution that would work for all vehicles.
For example, the repair procedures that worked for a P0142 on a Toyota Camry may not clear a P0142 on a Chevy Suburban. Remember that vehicle engines and their components may be structured differently per vehicle manufacturer.
If you plan on doing the repairs yourself, we recommend consulting vehicle-specific repair manuals or getting an online repair database subscription. These materials will provide you with reliable repair information about this trouble code.