P2231 – Heated oxygen sensor (H028) 1, bank 1 – signal circuit shorted to heater circuit / – no signal

Randy Worner

By Randy Worner (Contact Me)
Last Updated 2022-06-07
ASE/ACA World Class Technician

CodeFault LocationProbable Cause
P2231 Heated oxygen sensor (H028) 1, bank 1 - signal circuit shorted to heater circuit / - no signal
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Wiring, H025 / Wiring, H025, ECM

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What Does Code P2231 Mean?

This generic powertrain/engine diagnostic trouble code typically applies to most manufacturers since 1996, but more commonly found on BMW and Volkswagen models prior to 2010.

This code is focused on the voltage being returned by the Oxygen Sensor (O2S) to the engine controller (ECM/PCM). The PCM monitors the voltage and the sensor’s ability to send both a low voltage (typically below 2.5V) and a high voltage (above 2.5V). The oxygen sensor must be at a certain temperature in order to operate correctly. The oxygen sensor has a heater inside to help the sensor get up to operating temperature faster. The PCM applies 12 volts to this heating element. When the PCM detects the heater circuit is not operating correctly, it will set code P2231.

Where is the P2231 sensor located?

On most vehicles the Bank 1 Sensor 1 Oxygen Sensor is screwed into the exhaust manifold/pipe that attaches to the head that has the cylinder number 1 in it. In all cases, the Oxygen sensor that is responsible for this code will be in the exhaust system before the first catalytic converter.

Typically, the causes for this code to set are:

  • Oxygen sensor – O2 heater wire not getting 12-volt signal from PCM / failed O2 sensor – most likely
  • Wiring to the Oxygen sensor – likely
  • Failed PCM – unlikely

What are the common causes of code P2231?

  • It has been noted on certain BMW vehicles the PCM may need to be reprogrammed in order to alleviate this issue. The second most common is the Oxygen Sensor itself.
  • The most common part affected on all other makes and models is the Bank 1 Sensor 1 Oxygen Sensor itself.
  • If the sensor has been replaced and the fault code still exists, verify new sensor quality and operation. If all else fails, obtain a sensor from the OEM.
  • The second most common part is wiring to the Oxygen sensor heater circuit -damaged/chaffed/cut/abraded
  • Last part affected can be the PCM itself
  • If fault code persists, refer to basic fault code diagnosis / procedures for your manufacturer.