P0142 is a generic OBD-II trouble code indicating a malfunction in the oxygen sensor circuit for Bank 1 Sensor 3 (B1S3). The exact sensor location and circuit design can vary by vehicle.
P0142 Fault Code Description
P0142 indicates that the ECM/PCM has detected an abnormal condition in the electrical circuit or signal of the Bank 1 Sensor 3 oxygen sensor.
Code: P0142
System: Powertrain / Emissions
Sensor: Bank 1 Sensor 3
P0142 Symptoms
- Check Engine Light
- Increased emissions
- Possible reduction in fuel economy
- Possible emissions-test failure
- Usually limited drivability symptoms
P0142 Common Causes
- Faulty Bank 1 Sensor 3 oxygen sensor
- Damaged or corroded sensor wiring
- Loose or contaminated connector
- Open or shorted signal circuit
- Wiring damaged by exhaust heat
- Exhaust leakage near the sensor
- Power or ground problem
- Rare ECM/PCM or circuit-control fault
P0142 Severity
Low to Moderate. P0142 commonly illuminates the Check Engine Light and can affect emissions. Serious drivability problems are not typical, but the fault should be diagnosed rather than ignored.
P0142 Average Repair Cost
A typical repair may cost approximately $100–$400, depending on whether the repair involves wiring, a connector, or oxygen sensor replacement.
Actual cost varies by vehicle, labor rate, sensor design, and location.
P0142 Diagnosis
P0142 Visual Inspection
Inspect the B1S3 connector and wiring for corrosion, broken wires, loose terminals, melted insulation, or damage from exhaust heat.
P0142 Scan Tool and Live Data
Monitor Bank 1 Sensor 3 with a scan tool under the manufacturer's specified operating conditions. Compare the sensor behavior with related oxygen-sensor data.
P0142 Electrical Circuit Test
Use the vehicle-specific wiring diagram to identify the signal, ground, heater power, and heater ground circuits. Test continuity, power, and ground as applicable.
P0142 Exhaust Inspection
Inspect the exhaust system around the sensor for leaks that could affect oxygen-sensor readings.
P0142 Repair Verification
After the repair, clear the DTC and complete the required drive cycle or monitor test to verify that P0142 does not return.
P0142 Common Repairs
- Repair damaged oxygen-sensor wiring
- Repair or replace a damaged connector
- Repair an open or shorted circuit
- Repair an exhaust leak
- Replace the B1S3 oxygen sensor when testing confirms failure
- Repair a confirmed circuit-control problem
P0142 Related Codes
P0140 – O2 Sensor Circuit No Activity Detected, Bank 1 Sensor 2
P0141 – O2 Sensor Heater Circuit Malfunction, Bank 1 Sensor 2
P0146 – O2 Sensor Circuit No Activity Detected, Bank 1 Sensor 3
P0147 – O2 Sensor Heater Circuit Malfunction, Bank 1 Sensor 3
P0142 FAQ
Can I drive with P0142?
The vehicle can usually be driven for a limited period if it runs normally, but the fault should be diagnosed because emissions may be affected.
Does P0142 always mean the O2 sensor is bad?
No. Wiring, connectors, power, ground, exhaust leaks, and circuit faults can also cause P0142.
Where is Bank 1 Sensor 3 for P0142?
The exact location varies by vehicle. Sensor 3 refers to a third oxygen sensor position on Bank 1 on vehicles equipped with that configuration. Always verify its location using vehicle-specific service information.
Is P0142 the same as P0146?
No. P0142 indicates an oxygen sensor circuit malfunction, while P0146 specifically indicates no activity detected from Bank 1 Sensor 3.
Should I replace the sensor for P0142?
Not immediately. Test the wiring, connector, exhaust system, and electrical circuit before replacing the sensor.
P0142 Vehicles Affected
P0142 can appear on vehicles equipped with a Bank 1 Sensor 3 oxygen sensor. The exact sensor location, wiring configuration, and diagnostic strategy vary by manufacturer and engine.
- Some Toyota and Lexus vehicles
- Some Nissan and Infiniti vehicles
- Some Honda and Acura vehicles
- Some Ford and Lincoln vehicles
- Some Chevrolet and GMC vehicles
- Some Dodge, Chrysler, and Jeep vehicles
- Other vehicles equipped with multiple oxygen sensors
Vehicle coverage varies by engine, model year, emissions configuration, and market. Always verify P0142 compatibility and the exact B1S3 location using vehicle-specific service information.
P0142 Final Result
P0142 indicates a malfunction involving the Bank 1 Sensor 3 oxygen sensor circuit. Start diagnosis with the wiring and connector, then check live data and the electrical circuit before replacing the sensor. Because Sensor 3 configurations vary between vehicles, always verify the exact sensor location and wiring diagram for the specific vehicle.
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