Skip the auto shop - Our mechanics make house calls

P0142 OBD-II Trouble Code: O2 Sensor Circuit Malfunction (Bank 1, Sensor 3)

Check Engine Light

Diagnostic Trouble Code (DTC): P0142

P0142 code definition

O2 Sensor Circuit Malfunction (Bank 1, Sensor 3)

What the P0142 code means

P0142 is the OBD-II generic code indicating the Engine Control Module (ECM) input from the O2 sensor circuit for bank 1 sensor 3 is not within specifications.

What causes the P0142 code?

  • The O2 sensor bank 1 sensor 3 is downstream of the last catalyst in the exhaust system; an exhaust leak before the sensor can cause the code from excessive oxygen getting into the exhaust stream.

  • The ECM detects a short or open circuit in the O2 bank 1 sensor 3 circuit.

What are the symptoms of the P0142 code?

  • The ECM does not use the input from this O2 sensor for controlling the engine fuel control, so this code should not account for any abnormal drive complaints.

  • The Check Engine Light will be illuminated, indicating a problem with the downstream catalyst O2 sensor 3 for bank 1.

How does a mechanic diagnose the P0142 code?

  • Checks electrical connections to the O2 bank 1 sensor 3

  • Checks the exhaust system before the O2 sensor for any exhaust leaks

  • Scans to see if codes P0143 and P0144 are present, or if the problem is intermittent, and can be ignored unless the problem returns

Follows the manufacturer's specific pinpoint tests for further diagnosis

Common mistakes when diagnosing the P0142 code?

Follow these simple guidelines to prevent misdiagnosis of code:

  • Scan for codes P0143 and P0144, and repair these codes first to complete the diagnosis.

  • Check for any exhaust leaks or damages to the exhaust before the O2 sensor that could cause the sensor to not work properly.

How serious is the P0142 code?

  • The code is for the sensor behind the last catalyst on bank 1 of the exhaust and may contribute to an excessive exhaust emission if the problem is the catalyst.

  • The code will not cause the engine to run any different in most circumstances.

  • The vehicle will fail emission testing, since the Check Engine Light is on.

  • The exhaust may have a leak and cause fumes to get into the passenger compartment.

What repairs can fix the P0142 code?

  • Checking and repairing exhaust leaks before the catalyst

  • Repairing or replacing the wiring or connection to the O2 sensor for bank 1 sensor 3

  • Replacing the O2 sensor

Additional comments for consideration regarding the P0142 code

The code P0142 will not cause a driveability problem since the code is in relation to the last catalyst in the exhaust performance; it is for cleaning the exhaust stream only, not for engine fuel control.

Need help with a P0142 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Shutterstock.com Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...


Related questions

Q: Dashboard is working partially

Hey there. It sounds like it is having serious wiring issues. It is quite possible that one or more wires shorted. This is a potentially dangerous situation, and should be inspected immediately before getting back on the road. If you...

Q: Getting P0107 on OBD-II, mostly when car is in reverse gear and the Check Engine Light switches on.

Hi and thanks for contacting YourMechanic. Check the manifold absolute pressure (MAP) sensor for any corrosion or burned pins. This is what the P0107 code is coming up for. Check for power to the sensor. Back probe the wires and...

Q: My MIL light came on and stayed on for about 2 weeks then went off

Hey there. When the computer detects a problem it will turn on the Check Engine Light and stores a code in the memory. If the problem is intermittent and only happened that one time then after a certain amount of...