Which Codes Will This Page Cover?
- P0036 HO2S Heater Control Circuit – Bank 1 Sensor 2
- P0037 HO2S Heater Control Circuit Low
- P0038 HO2S Heater Control Circuit High
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What Is the P0036 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
Diagnose
Difficulty of Inspecting
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The OBD code P0036 refers to the “HO2S Heater Control Circuit – Bank 1 Sensor 2” and sets when the Engine Control Module (ECM) detects a potential problem with the bank 1 secondary sensor or sensor 2 heater control circuit. Sensor 2 is also referred to as the downstream sensor as it is located after the catalytic converter. Bank 1 is the side of the engine that houses the number 1 cylinder. Modern vehicles use a heated oxygen sensor (HO2S) with a heating element that quickly brings the sensor up to operating temperature.
The downstream sensor is primarily used for post-catalyst monitoring and checks the oxygen content of the exhaust gas that exits the catalytic converter. Each HO2S compares the oxygen content of the surrounding air with the oxygen content found in the exhaust system. The heater circuit gets its power or ground by the ECM, quickly bringing the sensor up to operating temperature. The ECM controls the HO2S heater circuit based on the engine coolant temperature and engine load readings until it reaches its optimal operating temperature of 570 degrees Fahrenheit. The faster the heated oxygen sensor goes to that temperature, the quicker the sensor starts sending accurate signals. If the ECM detects that the HO2S is not sending the proper signal or isn’t sending a signal at all, it will trigger the P0036 code.
What Are the Symptoms of a P0036 Code?
One of the most common symptoms of the P0036 code is that the ECM will illuminate your vehicle’s Check Engine Light. You will also notice a decrease in the engine performance in your car, as well as increased fuel consumption. You may also find that the catalytic converter cannot perform as efficiently as usual. The ECM could also trigger a failsafe mode for your vehicle. A failsafe mode limits your car to a specific operating range and will cause driveability issues. Finally, your vehicle will more than likely fail emissions testing because of the changes to the exhaust content.
What Are Some Causes of a P0036 Code?
Faults in the H2OS secondary sensor, or an open circuit inside the oxygen sensor, usually cause the P0036 code. Sometimes, an exhaust system ground strap may become corroded, triggering the ECM to set the code. If the wiring leading to the secondary sensor is damaged, the code could also be set. Finally, if there is any wiring failure or high resistance in the heated oxygen sensor, the ECM will set the P0036 code.
Can I Still Drive with a P0036 Code?
As we mentioned, the P0036 can lead to your vehicle going into a failsafe mode, which causes poor driveability. Oxygen sensors are important here because they heat up with the rising exhaust temperatures and operate as intended as long as the sensor is not negatively affected by some other problem. With that said, the heater is just for initial startups when the vehicle is cold. You shouldn’t drive your vehicle for prolonged periods with this code set because you can cause other components in the engine to stop working altogether. Instead, take your car to a qualified service center as soon as you see the P0036 code to prevent further damage to your engine and more costly vehicle repairs.
How Easy Is It to Diagnose a P0036 Code?
Diagnosing the P0036 code will require OBD code scanners and other tools that certified technicians would have readily available. The first thing a technician will do is reset the code and test drive the vehicle to see if the code reappears. Next, they will check the voltage from the fused battery feed to the heating element if it does. If there is no voltage, they will fix the open or short in that circuit. They will also look for blown fuses and check the functionality of the heated oxygen sensor. A lot of the problems related to this code are wiring-related because of the excessive exhaust heat, so the technician will make sure to check the wiring in the heating circuit.
How Difficult Is It to Inspect a P0036 Code?
Qualified technicians should be the ones to inspect your vehicle since the process involves multiple steps and tools. It would be best if you didn’t attempt to DIY this inspection at home because you could cause further damage to your engine.
A technician will first test the resistance in the heater circuit using a wiring diagram for reference. The heater circuit should have some resistance. If there is excessive resistance, there is an open circuit in the heating element and the oxygen sensor needs replacing.
They may also back-test the ground wire at the connector and inspect the resistance between the ground and the connector to the oxygen sensor. Checking the power to the oxygen sensor is a part of this process and any issues here indicate problems with the sensor or the ECM itself. With that said, you have to be careful whenever there is back probing, as incorrectly identifying the wires or some tests can cause damage to the heater driver. In either case, the technician will replace what needs replacing and retest the system for the issue.
Need Additional Help with Your P0036 Code?
Drivers should not take the P0036 code lightly as it can lead to severe vehicle damage. Hopefully, by following our guide here, you’ll be able to spot the signs related to this OBD code issue and have your car inspected by qualified technicians to keep it running.
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