Technical Description of OBD-II Trouble Code
The sensor power supply circuit B is experiencing high voltage levels.
What does that mean?
This is a generic diagnostic trouble code (DTC) that is applicable to many OBD-II vehicles manufactured from 1996 onwards. This includes vehicles from various manufacturers such as Buick, Chevrolet, Chrysler, Fiat, Ford, GMC, and Mercedes-Benz, among others. While the code is generic, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
When a vehicle equipped with OBD-II has stored the code P06B5, it indicates that the powertrain control module (PCM) has detected a voltage level that exceeds the maximum parameters for a particular sensor or group of sensors. The sensor(s) in question may be related to systems such as the exhaust gas recirculation system, heated exhaust oxygen sensor system, automatic transmission, or transfer case (only applicable to four-wheel drive or all-wheel drive vehicles). The affected sensor circuit is designated as B (A & B may also be interchangeable).
Most OBD-II sensors are activated by a voltage signal provided by the PCM or another on-board controller. The voltage applied, also known as the reference voltage, can range from very low voltage (typically measured in millivolts) to the full battery voltage. The most common sensor voltage signal is 5 volts, followed closely by battery voltage. It is important to determine the specific sensor related to this code, which can be obtained from a reliable source of vehicle information.
If the PCM or any other on-board controller detects a voltage level that exceeds the maximum parameters on the power supply circuit designated as B, the code P06B5 may be stored and the service engine soon/malfunction indicator lamp (SES/MIL) may illuminate. Illumination of the SES/MIL may require multiple ignition cycles with a failure.
A typical PCM powertrain control module, opened up:
What is the severity of this DTC?
This code can be categorized as severe. The wide range of sensors involved makes it difficult, if not impossible, to determine the exact severity of the symptoms caused by the condition that led to the storage of the P06B5 code.
What are some of the symptoms of the code?
Symptoms that may be experienced with a P06B5 trouble code include:
What are some of the common causes of the code?
Possible causes for this code include:
What are some P06B5 troubleshooting steps?
Prior to diagnosing the stored P06B5 code, it is important to diagnose and repair any other sensor-related codes.
To accurately diagnose a P06B5 code, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
If you do not have the means to reprogram controllers, it may be challenging to reach an accurate diagnostic conclusion for the stored P06B5 code. It is recommended to search for technical service bulletins (TSB) that match the stored code, vehicle information (year, make, model, and engine), and exhibited symptoms. This information can be found in your vehicle information source. If you find the appropriate TSB, it can provide valuable diagnostic information.
Connect the scanner to the vehicle diagnostic port and retrieve all stored codes and relevant freeze frame data. After noting down this information (in case the code is intermittent), clear the codes and test drive the vehicle. One of two outcomes will occur: the code will be restored or the PCM will enter readiness mode.
If the PCM enters readiness mode (indicating an intermittent code), the code may be more difficult to diagnose. The condition that caused the P06B5 code to be stored may need to worsen before an accurate diagnostic conclusion can be reached. However, if the code is restored, continue with the diagnosis.
Obtain connector face views, connector pinout charts, component locators, wiring diagrams, and diagnostic flow charts specific to the code and vehicle in question from your source of vehicle information.
Visually inspect all related wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged. It is also recommended to check chassis and engine grounds and make any necessary repairs before proceeding. Use your vehicle information source to obtain ground junction locations for related circuits.
If no other codes are stored and the P06B5 code continues to reset, use the DVOM to test controller power supply fuses and relays. Replace any blown fuses, relays, and fusible links as necessary. It is important to test fuses with the circuit loaded to avoid misdiagnosis.
If all controller power (input) and ground circuits are intact and there is excessive sensor power supply voltage being output from the PCM or another controller, a defective controller or controller programming error may be suspected. Keep in mind that replacing a controller will require reprogramming. Reprogrammed controllers may be available through aftermarket sources for some applications, while other vehicles/controllers may require on-board reprogramming that can only be done through a dealership or other qualified source.
Visually inspect system controllers for signs of water, heat, or collision damage. Any controller showing signs of damage should be considered defective.
