P0161 - OBD Trouble Code

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The major symptom of OBD code P0161 is the increased emission coming from the vehicle due to the oxygen sensor taking longer to reach its operating temperature. This increase in emissions due to problem in the heater control circuit, is what causes the Check Engine Light to come on so that the vehicle can be repaired as soon as possible.

OBD-II Code P0161 is defined as a Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)

The purpose of the oxygen sensor is to measure the oxygen content in the exhaust gases after they leave the combustion process of the engine. The oxygen sensor must be at a certain temperature in order for this information to be accurate. The oxygen sensor has a heater wire inside to help bring the sensor up to temperature quicker.

Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees Fahrenheit to generate an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM).

What cause the problem of O2 Sensor Circuit Malfunction?

• Faulty Heated Oxygen Sensor due to circuit problems
• Sensor wiring and harness short problem
• Poor electrical connections to the sensor
• Heated Oxygen Sensor (H2OS) damaged circuit fuse
• Problematic Engine Control Module hampering the engine performance

1. Heated Oxygen Sensor - The oxygen sensor controls and contributes to many different engine functions, including fuel/air mixture, engine timing and engine combustion intervals. A faulty sensor is a major reason behind the OBD Error Code P0161 flashing on the ECM and immediate replacement is advisable.
2. Mass Air Flow Sensor - If the sensor is unable to measure the air flow pressure correctly, it will hamper the air intake system and fuel delivery system. Replace faulty sensors immediately.
3. Manifold Absolute Pressure Sensor - Problematic MAP sensor can cause excessive fuel consumption, lack of power, and increased emission from the exhaust. Thus, replace faulty sensors now!
4. Fuel Pump - Always check for faults in the fuel pump as it can cause affected fuel delivery system and thus the combustion process, increasing the emission. Replace faulty pump now!
5. Engine Control Module - OBD Error Code P0161 can also be due to faulty ECMs. This may lead to engine stalling or not starting, and check engine lights being on. It’s better to get the faulty electricals replaced as soon as possible.
6. Powertrain Control Module - P0161 error code also relates to problems with the powertrain. Find all the Powertrain related parts with us.
7. Catalytic Converter - Catalytic converters can overheat because of excessive amounts of unburned gas caused by a misfiring spark plug or a leaky exhaust valve. In addition, a faulty oxygen sensor can cause overheating. Replace your old catalytic converter now!
8. Diagnostic Tool - In order to be that DIY guy, you need a few diagnostic tools to get your car problems pointed out easily. Our diagnostic tools collection will come handy. So why not have a look?

The most common symptoms include MIL (Malfunction indicator lamp) illumination. It is difficult to notice any other symptom associated with the failure of the heated circuit since it only runs momentarily when the vehicle is first started. This sensor is also after the catalytic converter, so it can affect the air/fuel ratio input to the PCM/ECM and is primarily used to check the efficiency of the catalytic converter

Following are the steps to be followed to correct the OBD code P0161 error;

• Inspect the oxygen sensor wiring for damaged or loose wiring to the sensor and test the resistance of the heater circuit using a wiring diagram for reference.
• If the heater circuit inside the sensor has some resistance present, excessive resistance or an over limit reading, it would indicate faulty oxygen sensor will need to be replaced.
• Check for power supply to the oxygen sensor. If no power is present at the connector during cold start, there may be a problem with the power supply circuit to the oxygen sensor or the PCM itself which need immediate replacement.

However, if you face any of these issues then visit us at Parts Avatar Canada. We have stocked a wide range of best priced oxygen sensors, ECM/PCM parts and a lot more to help you out in fixing your car.

• The first step is to complete a visual inspection of the wiring for the bank 2 sensor 2 oxygen sensor.
• Many times, this code can be set due to damaged wirings which are wrongly routed or damaged by road hazards.
• The next step is to measure the resistance of the heater circuit in the oxygen sensor itself.
• If the resistance of the sensor is not as per the specifications then it is faulty and the oxygen sensor is needed to be replaced.
• If the sensor checks out to be in perfect condition, then we must check the resistance of the rest of the circuit from powertrain control module to the connector of the bank 2 sensor 2 oxygen sensor. A normal reading for wiring is less than half an ohm.
• If the rest of the wiring is found to be good then the likely problem is with the powertrain control module itself.

Common Mistakes When Diagnosing The P0161 Code

Though the sensor itself is generally the cause of P0161, using the proper tools and following the complete diagnostic procedure without skipping any steps is required as to avoid unneeded repairs. Monitoring the sensor data from the scan tool live data stream is the only way to check for proper operation, and the sensor should not be replaced until it is tested.

P0161 has easily managed symptoms but like any other code, it should be repaired at the earliest convenience. In rare cases where the vehicle runs poorly and the fuel economy goes down, caution is advised when driving to avoid any issues.

P0160 - O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)