Technical Description of OBD-II Trouble Code
The O2 Sensor Positive Current Control Circuit for Bank 2 Sensor 1 is registering a low voltage.
What does that mean?
This is a generic diagnostic trouble code (DTC) that applies to many OBD-II vehicles (1996-newer), including Mazda, VW, Acura, Kia, Toyota, BMW, Peugeot, Lexus, Audi, etc. The exact repair steps may vary depending on the year, make, model, and powertrain of the vehicle.
A stored code P2241 indicates that the powertrain control module (PCM) has detected a positive current discrepancy in the upstream oxygen (O2) sensor for engine bank number two. Bank two refers to the engine bank that does not contain the number one cylinder. Sensor 1 refers to the upstream (pre) sensor. The positive current control circuit is a low voltage circuit.
The PCM uses data input from heated oxygen sensors (HO2S) to monitor the exhaust oxygen content for each engine bank and catalytic converter efficiency.
Oxygen sensors consist of a zirconium dioxide sensing element housed in a vented steel housing. Platinum electrodes are soldered between the sensing element and wire leads in the oxygen sensor harness connector. The O2 sensor harness connector plugs into the controller area network (CAN), which connects the HO2S wiring harness to the PCM connector.
Each HO2S is threaded or studded into an exhaust pipe or manifold, positioned so that the sensing element is near the center of the pipe. Exhaust gases flow over the oxygen sensors, entering through vent holes in the steel housing and swirling around the sensing element. The air fills a tiny chamber in the middle of the sensor, where the heated air forces the oxygen ions to produce energy recognized by the PCM as voltage.
Variations in the number of oxygen ions in ambient air and exhaust cause the heated oxygen ions inside the HO2S to rapidly shift between platinum layers. These shifts result in variations in HO2S output voltage, which the PCM interprets as changes in exhaust oxygen concentration.
Voltage signal outputs from the HO2S are lower when more oxygen is present in the exhaust (lean condition) and higher when less oxygen is present (rich condition). This portion of the HO2S uses low voltage (less than one-volt).
In a separate section of the sensor, the HO2S is preheated using battery voltage (12-volts) to monitor exhaust oxygen content faster when the engine temperature is low.
If the PCM detects a voltage that is too low and does not meet acceptable parameters, a P2241 code will be stored, and a malfunction indicator lamp (MIL) may illuminate. Most vehicles require multiple ignition cycles with a failure for MIL illumination.
A typical O2 Oxygen Sensor:
What is the severity of this DTC?
An HO2S with a control circuit problem can result in a poorly running engine and various drivability issues. A code P2241 should be considered severe and addressed promptly.
What are some of the symptoms of the code?
Symptoms of a P2241 trouble code may include:
What are some of the common causes of the code?
Possible causes for this code include:
What are some P2241 troubleshooting steps?
To accurately diagnose a code P2241, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and reliable vehicle information.
Connect the scanner to the vehicle diagnostic port and retrieve all stored codes and relevant freeze frame data. Write down this information in case the code is intermittent. Clear the codes and test drive the vehicle. Either the code P2241 will be reset or the PCM will enter readiness mode.
If the code is intermittent and the PCM enters readiness mode, it may be more challenging to diagnose. The conditions that caused the P2241 to be stored may need to worsen before an accurate diagnosis can be made. If the code is reset, continue with the diagnosis.
Use your source of vehicle information to access connector face views, connector pinout charts, component locator charts, wiring diagrams, and diagnostic flow charts specific to the code and vehicle in question.
Perform a visual inspection of HO2S-related wiring and connectors. Replace any wiring that is cut, burned, or damaged.
Unplug the HO2S in question and use the DVOM to check resistance between the positive current control circuit and any ground circuits. If there is continuity, suspect a defective HO2S.
If the code P2241 continues to be reset, start the engine and allow it to reach normal operating temperature and idle (with the transmission in neutral or park). Connect the scanner to the vehicle diagnostic port and observe oxygen sensor input data on the data stream. Narrow the scope of the data stream to include only pertinent data for a faster response.
If the oxygen sensors are functioning normally, voltage on pre-oxygen sensors will cycle continuously between 1 and 900 millivolts once the PCM enters closed loop operation. Post sensors will also cycle between 1 and 900 millivolts but will settle at a certain point and remain relatively stable compared to the pre-sensors. HO2S that fail to cycle adequately should be considered defective if the engine is in good working order.
If the HO2S displays battery voltage or no voltage on the scanner data stream, use the DVOM to obtain live data from the HO2S connector. If the output data remains the same, suspect an internal HO2S short that will require replacement of the HO2S.
