What Does P0143 Code Mean?
OBDII code P0143 – O2 Sensor Circuit Low Voltage is a diagnostic trouble code (DTC) that indicates a problem with the oxygen sensor circuit in bank 1 sensor 3 of a vehicle’s engine. This code is typically associated with vehicles that have a V6 or V8 engine configuration, and it usually occurs in vehicles that were manufactured in the late 1990s or early 2000s.Specifically, the P0143 code translates to O2 Sensor Circuit Low Voltage or an issue with your 02 sensor. In this article, we will discuss what the P0143 code means, what could cause it, and how to diagnose and fix the problem.
Fault Code Definition O2 Sensor Circuit Low Voltage
The Rear Catalyst Monitoring Oxygen Sensor evaluates the rearmost Catalytic Converter’s emissions-reducing capability in a system with two Catalytic Converters for each bank of cylinders. P0143 is set when the Rear Oxygen Sensor voltage signal remains below 200 millivolts for an extended period of time.P0143 can also be triggered by an existing issue, or related trouble code. P0135 for O2 Sensor Heater Circuit is another sign that something with your vehicle is not functioning properly.
How to diagnose and fix the P0143 code?
To diagnose and fix the P0143 code, follow these steps:
- Check for other codes: Before diagnosing the P0143 code, check for any other codes that may be present. If there are multiple codes, address them in the order they were stored.
- Inspect the oxygen sensor: Inspect the oxygen sensor for signs of damage or contamination. If the sensor is damaged, replace it with a new one.
- Check the wiring and connector: Inspect the wiring and connector that connects the oxygen sensor to the PCM. Look for any damage, corrosion, or loose connections. Repair or replace any damaged components.
- Test the oxygen sensor circuit: Use a multimeter to test the oxygen sensor circuit. Check for proper voltage and ground signals. If the circuit is open or shorted, repair the wiring or replace the sensor.
- Test the PCM: If all other components check out, test the PCM for proper operation. This typically requires a specialized scan tool and advanced knowledge of vehicle electronics.
P0143 Symptoms
Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed
In some cases, the vehicle will fail an Emissions Test
In many cases, the NOx emissions will be elevated
Common Problems That Trigger the P0143 Code
Defective Rear Most Oxygen Sensor
Faulty Rear Most Oxygen Sensor wiring or connections
Common Misdiagnoses
Oxygen Sensor is replaced when the problem is faulty sensor wiring or connections
Rear Catalytic Converter is replaced when the problem is an exhaust leak before the Rear Oxygen Sensor
Once the problem has been diagnosed and fixed, clear the code from the PCM and test drive the vehicle to ensure that the issue has been resolved.
In conclusion, the P0143 O2 Sensor Circuit Low Voltage code indicates a problem with the oxygen sensor. This sensor is otherwise known as the circuit in bank 1 sensor 3. This can be caused by a failed oxygen sensor, wiring or connector issues, or a faulty PCM. By following the steps outlined in this article, you can diagnose and fix the problem and ensure that your vehicle is running smoothly and efficiently.
