P0142
Fix within 1-2 weeksThe engine computer isn't receiving the correct electrical signal from the third oxygen sensor on the first bank of the engine.
Code P0142 means your engine computer isn't getting a signal from the third O2 sensor. Common causes: Bad O2 sensor (70%), wiring issues (20%). Drivability: Yes, safe to drive. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0142?
Yes, safe to drive
No restrictions
Stop driving immediately if: Flashing Check Engine Light (indicates a severe misfire), loud exhaust noises, burning smell, significant power loss.
Symptoms of P0142
- 1Check Engine Light is on
- 2No noticeable drivability issues
- 3Failed emissions test
Common Causes of P0142
Parts most likely causing this code, ranked by probability
The oxygen sensor itself has failed and is no longer sending a proper signal to the engine computer.
70% of P0142 cases are fixed by replacing this part
Damaged, corroded, or loose wiring or connectors to the oxygen sensor prevent the signal from reaching the engine computer.
20% of P0142 cases are fixed by repairing wiring or connectors
An exhaust leak near the oxygen sensor can allow outside air to enter the exhaust stream, skewing sensor readings and triggering a circuit malfunction code.
5% of P0142 cases are fixed by repairing an exhaust leak
A rare internal fault within the engine computer can prevent it from correctly reading the oxygen sensor signal.
5% of P0142 cases are fixed by replacing the ECM/PCM
Check These First (Before Buying Parts)
- Visually inspect the Bank 1 Sensor 3 oxygen sensor and its wiring for any obvious damage, fraying, or loose connections.
- Listen for any exhaust leaks near the sensor. A leak can sometimes cause incorrect readings.
How to Diagnose P0142
- 1Visually inspect the Bank 1 Sensor 3 oxygen sensor and its wiring for any damage, corrosion, or loose connections.
- 2Check for any exhaust leaks near the oxygen sensor by listening for hissing sounds or using a smoke machine.
- 3Use an OBD-II scan tool to monitor the live data from Bank 1 Sensor 3. Look for erratic, stuck, or no voltage readings.
- 4Test the resistance of the oxygen sensor's heater circuit and signal circuit with a multimeter.
- 5Check for continuity and proper voltage at the oxygen sensor connector using a multimeter.
P0142 on Popular Vehicles
Toyota Camry
2007-2024Oxygen sensor failures are common on these models as they age. The sensor is typically accessible under the vehicle.
75% fixed by replacing the oxygen sensor
Honda Accord
2003-2024Similar to Toyota, the Bank 1 Sensor 3 oxygen sensor is a frequent culprit for P0142. Check for exhaust leaks around the sensor as well.
70% fixed by replacing the oxygen sensor
Ford F-150
2004-2024On F-150s, P0142 can be due to a failed O2 sensor, but also pay close attention to wiring integrity, especially in areas exposed to road debris or harsh conditions.
65% fixed by replacing the oxygen sensor
Frequently Asked Questions
What does P0142 mean?
P0142 indicates that the engine's computer has detected a malfunction in the circuit of the third oxygen sensor on Bank 1. This sensor is typically located after the catalytic converter and monitors its efficiency.
Can I drive with P0142?
Yes, you can drive safely with a P0142 code. This code usually does not cause immediate drivability issues or leave you stranded. However, it affects your vehicle's emissions monitoring.
Will P0142 clear itself?
No, P0142 will not clear itself. The engine computer needs to see a correct signal from the oxygen sensor for a specific number of drive cycles before the code will clear. You will need to diagnose and fix the underlying issue.
How do I fix P0142 myself?
Start by visually inspecting the oxygen sensor and its wiring for damage. If no issues are found, the most common fix is replacing the Bank 1 Sensor 3 oxygen sensor. Ensure the new sensor is properly installed and the connector is secure.
How much does it cost to fix P0142?
A DIY fix for P0142, typically involving replacing the oxygen sensor, costs $50-$200 for the part. Professional repair at a shop will cost $150-$500, including parts and labor.
P0142 keeps coming back - why?
If P0142 keeps returning, it means the underlying issue was not fully resolved. Common reasons include a faulty replacement sensor, persistent wiring damage, an overlooked exhaust leak, or a rare issue with the engine computer itself.
Will P0142 fail emissions/smog test?
Yes, P0142 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on, regardless of the code, is an automatic failure in most jurisdictions.
What's the difference between P0142 and P0420?
P0142 indicates a circuit malfunction with the oxygen sensor itself, meaning the computer isn't getting a proper signal. P0420 indicates a catalytic converter efficiency issue, meaning the sensor is working but reporting that the converter is not performing as it should.
P0142 on Toyota Camry?
On Toyota Camry models, P0142 is often caused by a failed Bank 1 Sensor 3 oxygen sensor. These sensors are wear items and can fail over time, especially on higher mileage vehicles. Wiring issues are less common but still possible.
Questions to Ask Your Mechanic
Did you check the live data from Bank 1 Sensor 3 with a scan tool?
Good answer: Yes, the sensor voltage was stuck at 0.45V (or another specific value) or showed no activity, indicating a circuit issue.
Did you inspect the wiring and connector for corrosion or damage?
Good answer: Yes, I checked the harness from the sensor all the way to the ECM and found no visible damage or corrosion.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-2 hours
Intermediate - requires specific tools like an O2 sensor socket and an OBD-II scan tool for proper diagnosis and verification.
Cost of Waiting
Ignoring P0142 means your vehicle's emissions system is not being properly monitored. This will cause you to fail emissions testing. While it doesn't usually cause immediate engine damage, it can mask other issues that might lead to reduced fuel economy or, in rare cases, contribute to premature catalytic converter wear if the underlying issue is a rich/lean condition that the sensor isn't reporting.
While You're In There...
If you find an exhaust leak or need to remove exhaust components to access the sensor, replacing old gaskets prevents future leaks and ensures a tight seal.
Applying anti-seize to the threads of the new oxygen sensor prevents it from seizing in the exhaust pipe, making future removal much easier.
Tools You'll Need
- OBD-II Scan Tool
- Oxygen Sensor Socket
- Ratchet
- Wrench Set
- Wire Brush
- Anti-Seize Compound
- Multimeter (optional, for advanced diagnostics)
P0142 is a common emissions code. Most repairs are straightforward, often just replacing the oxygen sensor, and your vehicle will be back to monitoring emissions correctly.
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Your Next Steps
Step 1: Perform a thorough visual inspection of the Bank 1 Sensor 3 oxygen sensor and its entire wiring harness. Look for cuts, burns, corrosion, or signs of rodent damage.
Step 2: If the visual inspection doesn't reveal any issues, use an OBD-II scan tool to monitor the live data from the sensor. If the sensor shows no activity or a fixed voltage, proceed with replacing the oxygen sensor.
Step 3: If replacing the sensor doesn't resolve the code, you will need to test the wiring for continuity and proper voltage. If wiring is good, a rare ECM/PCM issue might be present.