Definition of Trouble Code P0143
Trouble code P0143 refers to an issue with the oxygen sensor circuit. Specifically,
it indicates low voltage in Bank 1 Sensor 3. Oxygen sensors monitor the level of
oxygen in the exhaust gases, allowing the engine control module (ECM) to adjust
the air-fuel mixture for optimal efficiency and emissions. This code suggests that
the ECM is receiving a lower voltage signal than expected from the sensor, which
can affect the vehicle's performance and emissions.
Diagnosing Trouble Code P0143
Diagnosing trouble code P0143 involves several steps to pinpoint the source of
the issue. Before starting, gather the necessary tools and equipment, such as an
OBD-II scanner, a digital multimeter, and a repair manual specific to your vehicle.
Step 1: Verify the code
Begin by connecting the OBD-II scanner to the vehicle's diagnostic port and scanning
for any stored trouble codes. If P0143 is present, proceed to the next step.
Step 2: Inspect the oxygen sensor wiring and connections
Visually inspect the wiring and connections related to Bank 1 Sensor 3. Look
for signs of damage, corrosion, or loose connections. If any issues are found, repair
or replace the damaged components as necessary.
Step 3: Test the oxygen sensor voltage
Refer to your vehicle's repair manual to locate Bank 1 Sensor 3. With the engine
running and at operating temperature, use a digital multimeter to measure the sensor's
voltage output. The voltage should fluctuate between approximately 0.1 and 0.9 volts.
If the voltage is consistently low, the sensor is likely faulty and needs replacement.
Step 4: Check the sensor heater circuit
Some oxygen sensors are equipped with internal heaters to reach operating temperature
faster. Consult your repair manual for the specific resistance value of the heater
circuit. Using a digital multimeter, measure the resistance across the heater circuit
terminals. If the resistance is outside the specified range, replace the sensor.
Repairing Trouble Code P0143
After diagnosing the source of the issue, take the necessary steps to repair
it. Common solutions for trouble code P0143 include:
1. Replace the oxygen sensor
If the diagnosis indicates a faulty oxygen sensor, replace Bank 1 Sensor 3. Follow
your repair manual's instructions for proper replacement procedures.
2. Repair or replace damaged wiring or connections
If damaged wiring or connections were identified during the diagnosis, repair
or replace them as needed. Ensure all connections are secure and free from corrosion.
Trouble code P0143 - Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 3) can
affect your vehicle's performance and emissions. By following the provided step-by-step
guide, you can diagnose and repair the issue to restore your vehicle's efficiency.
Always consult your vehicle's repair manual for specific procedures and values related
to your make and model.