Skip the auto shop - Our mechanics make house calls

P2231 OBD-II Trouble Code: O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1

Check Engine Light

P2231 code definition

O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1

What the P2231 code means

P2231 is an OBD-II generic code for the engine control module (ECM) detecting the O2 sensor signal is shorted to the heater circuit on bank 1 sensor 1.

What causes the P2231 code?

  • The engine control module (ECM) monitors the O2 sensor bank 1 sensor 1 signal wire and is expecting only about 1.2 volts maximum. When the ECM sees a return voltage above 1.2 volts, it knows the sensor is shorted to the heater circuit that is running battery voltage. When it sees the short, the ECM turns on the Check Engine Light and the P2231 code is set.

  • The O2 sensor is shorted internally or the wiring is shorted.

What are the symptoms of the P2231 code?

  • The Check Engine Light will be illuminated and the code is set in the ECM memory as a fault.

  • The ECM will ignore the O2 sensor and use all the other O2 sensors to try and control the fuel or it will go into open loop fuel control.

  • The engine may hesitate on acceleration.

  • The fuel mileage may be more than before failure.

How does a mechanic diagnose the P2231 code?

  • Scans for codes and documents any codes in the ECM, then looks at the freeze frame data for failure.

  • Monitors the O2 sensors for bank 1 sensor 1 to see if the signal is shorted to the heater circuit.

  • Inspects the O2 sensor and the wire harness for any damage that could cause the short.

  • Follows the manufacturer pinpoint tests for the diagnosis and replacement of the O2 sensor if the O2 sensor is internally shorted.

Common mistakes when diagnosing the P2231 code

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired.

  • Failing to clear the ECM codes after the codes are fixed so the ECM will enable the system to control the fuel again.

How serious is the P2231 code?

Code P2231 is a code indicating the engine cannot control the fuel since it cannot go into a closed loop on bank 1. This will cause the engine to fail emissions testing and the engine to not run as efficient as it can.

What repairs can fix the P2231 code?

Additional comments for consideration regarding the P2231 code

Code P2231 is for a short in the bank 1 sensor 1 O2 sensor. The most common problems that cause this are issues with the sensor wiring or the sensor being contaminated by an oil leak. The short can also be from a harness that comes loose and melts on the exhaust. The sensor shorting is that last problem to look for. If an oil leak is the cause of the problem, then make sure you replace the O2 sensor and repair the oil leak so the problem will not happen again anytime soon.

Need help with a P2231 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

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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.


Post a question and get free advice from our certified mechanics.


More related articles

How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222 code means The manufacturer specifies a range of acceptable voltage to be produced from the throttle position...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...

Related questions

Q: P0139 HO2S-12 (Bank 1 Sensor 2) Circuit Slow Response - 2005 Honda Accord

This code indicates that the rear oxygen sensor is not properly reading the oxygen content and adjusting the air/fuel ratio as it is supposed to. This can be caused the by the sensor not working properly, the wiring to the...

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: Check engine light refuses to go off after engine replaced

Hello there, you have a long series of issues going on with your 2013 Hyundai Sonata. If you keep getting a repeating oil light on than there is likely a fault in that system. Since this fault has lasted after...