Code P0036 is a generic diagnostic trouble code (DTC) that’s set when there’s a potential fault in the downstream oxygen (O2) sensor’s heater circuit.
Have you recently read code P0036 on your OBD-II scanner? Find out what it means, what causes it, and what could be the possible symptoms you might face. Here are the things you need to know before troubleshooting the P0036 code.
What Does the Code P0036 Mean?
Diagnostic Trouble Code (DTC) P0036 Code stands for HO2S Heater Control Circuit (Bank 1 Sensor 2). The P0036 code gets set when the PCM perceives a potential problem with the bank 1 sensor 2 O2 sensor heater control circuit. Sensor 2, referred to as the downstream sensor, is after the catalytic converter while bank 1 points to the side where the cylinder #1 is located. Most modern vehicles use a heated oxygen sensor (HO2S) that has a heating element that quickly brings the sensor to operating temperatures.
Note: If you want to learn where Bank 1 is, you can read our guide here.
The downstream (post-converter) HO2S primarily gets used for post catalyst monitoring. It does this by checking the oxygen content of the exhaust gas after exiting the catalytic converter. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream.
The heater circuit may get supplied power or ground by the PCM, which brings the sensor up to operating temperature rather quickly. Typically, the PCM controls the HO2S’ heater circuit based on the signals from the engine coolant temperature and engine load.
The HO2S has to reach the optimal operating temperature (typically 570°F) to ensure that it’s sending accurate voltage signals to the PCM. The faster the heated oxygen sensor reaches that temperature, the faster the sensor will start sending an accurate signal. The heater circuit minimizes the time needed for this to happen.
You can learn more about how and why oxygen sensors are heated here.
If the PCM detects that the HO2S is not sending the right signal or not sending a signal at all, it will store code P0036 and illuminate the check engine light.
What are the Possible Causes of the P0036 Code?
Even though code P0036 is a generic code, meaning it applies to a variety of vehicles with on-board diagnostics, the reasons for its storage by the PCM can vary from one vehicle to another. A P0036 on a Chevrolet may differ from one on a Honda in terms of which component is causing the issue. Other factors may affect it, including the layout of a certain system and the overall design of the vehicle.
If you’re wondering why your OBD-II sensor is giving you a P0036 code, it could be one of these causes:
- A faulty oxygen sensor (a healthy heater usually measures about 6 ohms)
- A problem with the O2 sensor heater control circuit, such as damaged wires or poor connections
- An issue with the ECM, such as software in need of an update
Quick tip: Get an old O2 sensor connector and wire a small light bulb to the two wires that are the same color on the connector (white, brown, black, etc.). These two same-color wires are the wires that feed the heater. When you start the truck with this homemade tool plugged into the harness in place of the suspect sensor, the light should come on. If it doesn’t, find out why. Don’t neglect to check fuses.
What are the Common Symptoms of the P0036 Code?
There can be no observable symptoms for code P0036 other than the most common one you may get with any other DTCs, which is an illuminated check engine light. If you bring your car to an emissions testing facility, the check engine light may give you a failed result.
How to Diagnose the P0036 Code
To resolve the P0036 code, you need to pinpoint its exact cause first, but this can be a bit difficult. From a DIY-er point of view, it might appear to be simple and easy. However, for the emission control system of your car, you should not risk working on it alone. For better results and proper assessment, seek your trusted mechanic.
How to Fix the P0036 Code
There’s no single fix for the P0036 code, just like most OBD-II codes. This is why a lot of people leave the fixing to their mechanics. However, if you have the necessary tools and automotive DIY know-how, you can fix the P0036 code yourself.
You’ll need the help of online guides or repair manuals to help make sure you’re on the right track. You can also use a single-vehicle ALLDATA subscription, which should be useful for this fix and most other fixes you will need to do on your car.
Just remember that a fix that works on one car may not work on another vehicle.
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