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

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?

• Repairing the wiring harness and securing it away from exhaust system
• Replacing the O2 sensor for bank one.

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.

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