P0031 fault code and how to check oxygen sensor heater circuit

Shown here is P0031 fault code description and how to repair this oxygen sensor problem. Fixing this code requires basic knowledge in operation of the oxgen sensor and its heater wiring circuit.

P0031     Oxygen sensor heater Control Circuit

The P0031 fault code is about an oxygen sensor heater circuit failure located in bank 1 sensor 1. (bank 1 is at exhaust manifold by the #1 cylinder head, bank 2 is on the 2nd cylinder head). On some engines, both exhaust manifolds could have one oxygen sensor on each side on both cylinder heads

2). On the oxygen sensor itself, it has 4 wires which are color coded. Two of wires are for the heater circuit that heats the oxygen sensor to make it reach optimum operation quickly. Those 2 oxygen sensor heater wires could be shorted between the sensor and the ecm (engine computer) wirings or other engine components.

oxygen sensor heater

The common fix for this code is to check the integrity of the oxygen sensor heater wires. Check the wires for insulation and routing which could be loose or touching a hot engine exhaust that can short the wires. If the engine has too many miles, it is possible that the heater circuit inside is worn and shorted which needs 02 sensor replacement. If you have a DVOM, you can also test the continuity of the heater wires from the oxygen sensor to your computer connection pins.

More detailed fixes will be provided as soon as you give the symptoms of the P0031 fault code. 02 sensor replacement is expensive and ATS will provide the common fixes and wiring diagram so you can trace the wirings and fixed it properly. Use an obd2 code reader or scanner so you can access this P0031 fault code. When you have this obd2 fault code list, use it as a reference and give the code to ATS. We will then send you all the fixes for the obd2 trouble code. ATS has lots of fixes for domestic vehicles such as obd2 gm codes, obd2 ford codes, dodge obd2 codes and all obd2 import codes such as Toyota obd2 codes, Honda obd2 codes, Nissan obd2 codes, etc.

More TIPS about oxygen sensor symptoms

Oxygen sensor symptoms can be determined when the content of the engine exhaust gas indicates failure in fuel mixture when operating lean or rich. When the oxygen sensor detects that the engine is operating rich, the signal voltage is high, and any decreases in the signal voltage means the engine running is lean. The engine computer supplies a reference voltage like one volt or five volts, and then shows the change in the sensor return voltage as the sensor's resistance is changing. If you have connected everything properly, when you crank the engine, you should see the check engine light coming out.

Unheated oxygen sensors rely on the heat of the exhaust gases to reach the working temperature, therefore they might start to cool down while the engine is idling and revert back to a default air-fuel ratio setting. This type of sensor usually has a single wire connector, though others have two. Unlike the fuel pump relay, the 02 sensor heater circuits have a separate fuse for each sensor and grounds, which are controlled by the engine computer.

To read a voltage across the oxygen sensor heater, one side must be connected to (+) and one side must be connected to (-), which is accomplished by the computer or a transistor. It can read 12V between each wire and a separate ground if it was connected to positive and the other was not yet connected to ground connection (for details, please contact ATS).

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