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P0036 Fault Code (Causes & Fixes) Heated Oxygen Sensor (HO2s) Control Circuit

Updated: Jan 9

The "HO2S Heater Control Circuit - Bank 1 Sensor 2" OBD code P0036 is issued when the Engine Control Module (ECM) identifies a possible fault with the bank 1 secondary sensor or sensor 2 heater control circuit.


If a DTC is associated to the powertrain, an OBD scanner will read it as starting with P, thus the letter "P". Generic fault codes are those of the format P0xxx.
 

Table of Contents:

 

The Meaning of a P0036 Fault Code

The P0036 error code indicates that the heated oxygen sensor (HO2S) control circuit bank 1, sensor 2 is not transmitting the right data to the powertrain control module (PCM).


The engine exhaust should have a precise air-fuel ratio of 14.7 to 1 for the engine to function properly, and the HO2S (oxygen sensor) monitors the oxygen from the exhaust.


It's heated to guarantee the PCM maintains a fast reaction to the closed-loop system, lowering emissions during startup.


When there is a problem with the HO2S heating element, the error code P0036 appears.


Is It Serious?

This diagnostic code is usually classed as minor-to-moderate. Because the HO2S plays such a minor factor in determining how a vehicle runs, there are generally very few driveability symptoms.


As a result, the car may be driven, but it should be brought in for diagnostic and repair as soon as possible to avoid potential issues such as the following.


  • poor performance

  • lower fuel efficiency

  • sensor loop failure

  • damage to other components


Signs & Symptoms of P0036

While in many circumstances of OBD fault codes activating, there will be multiple signs and symptoms associated with the problem, this is not the case with the P0036. There may be few specific signs.


You may notice the following signs:

  • Check engine light (CEL) illumination

  • Poor performance and drivability

  • Lower fuel efficiency


Possible Causes of a P0036 Fault Code

There are a variety of possible causes, the following are the most typical reasons for the P0036 trouble code.


  • Engine bank HO2S sensor failure 2

  • Exhaust ground connection that is corroded

  • Faulty PCM sensors

  • Faulty wiring to the oxygen sensor (HO2S)

  • Water penetration causing the HO2S fuse to fail


Diagnosing the P0036 Trouble Code

Diagnosing a fault code is best done using a professional OBD scanner or by completing a diagnostic check with a skilled technician.


Many vehicles with over 80,000-100,000 miles have sensor faults that arise during start-up or sustained driving.


  1. Check to see if there are any technical service bulletins available for your vehicle's model and manufacture to see if there is a recognised fault with your car that may help you to address the problem.

  2. Scan your system for any more OBD fault codes. If any of these are present, they should be investigated also.

  3. Clear the error codes, then drive the vehicle while someone reads the live data with an OBD scanner.

  4. If the error continues, visually examine the wiring for broken or loose connections.

  5. Check the power and ground connections to the the sensor.

  6. Examine the HO2S heating element.


Testing the Wiring

With the key on and the engine off, use a digital voltmeter to check for a fused battery supply to the heater element of 12+ volts. If no voltage is present, fix any open or short circuit in the 12 volt feed, but first verify if any fuse blown by the short has to be replaced.


If the battery feed is correct, disconnect the ground (control) circuit from the ECM wire connection and inspect the circuit for resistance. Repair the open in the circuit if there is infinite resistance.


Possible Fixes for a P0036 Code

It is advised that you test drive the car after each fix to determine whether the fault code is resolved. If the code reappears, try the next repair option.


The following are the most typical fixes for a P0036 error code:

  1. Reset the trouble code after verifying the code using a professional OBD reader. After that, do a test drive to determine whether the issue code has been cleared.

  2. If the code appears, repair or replace any loose or broken wiring to the HO2S, check voltage and ground.

  3. If this does not resolve the issue, the HO2S should be replaced.