Diagnostic Trouble Code (DTC) P0131

Front Heated Oxygen Sensor Low Voltage



 Features of the Circuit


  • The ECM terminals 44 and 13 receive a voltage of nearly 450mm volts from the ECM
  • If the exhaust is rich then the oxygen sensor alters the voltage maximum by 1 volt.
  • If the exhaust is poor then the oxygen sensor alters the voltage maximum by 10mm volts.
  • The O2 sensor acts like an open circuit and does not generate any voltage when it is below 360°C(600°F).
  • An "open loop" operation is  created by an open O2 sensor circuit or a cold O2 sensor.



DTC sets under the following conditions:




When  1) The engine controls system is in closed loop.

When  1)  The engine controls system is in closed loop

           2)   Engine speed is less than 6,000rpm

            2) Engine speed is less than 6,000rpm

           3)     The oxygen sensor voltage is  below 0.07V for at least 40seconds     

            3)   The oxygen sensor voltage is between 0.352 and 0.499 at least 10 seconds  

           4)   DTCs P0107, P0108, P0117, P0118, P0122, P0123, P0335, P0336, P0341, P0342, P0400, P0404, P0405, P0406 are NOT SET.






Task Boosted When DTC sets

When Does DTC clear?

1) It will be found that the Malfunction Indicator Lamp (MIL) is glowing.

1)   The MIL will stop work after four repetitive ignition cycles where the diagnostic functions flawlessly.


2) The ECM is devised to record operating conditions at the time the diagnostic fails which will be stored in the Freeze Frame and Failure Records will be boosted.


2)  A history DTC will clear after 40 consecutive warm-up cycles without a fault

3) A history DTC is stored.


3)  The Scan Tool can be made use of in order to clear all DTCs

4) The coolant fan will turn ON.


4) Disconnecting the ECM battery feed for more than 10 seconds



Diagnostic Help Available:


  • The oxygen (O2) sensor wire must be clearly examined to help prevent an incorrect    placement or inaccurate contact of the exhaust manifold.
  • Probe if there is any intermittent ground in the wire between the O2 sensor and the engine control module.
  • So as to ascertain whether a restricted fuel injector is causing any lean condition an injector balance test must be undertaken.
  • A lean running condition may be the result of Vacuum of crankcase leaks.
  • Outside air may be sucked into the exhaust and past the sensor if there is any exhaust manifold gasket leak.
  • Normal scan tool voltage ranges between 0.1volts and 0.9 volts while in closed loop.