P06B6 Internal Control Module Knock Sensor 1 Processor Performance
OBD2 Error Codes

P06B6 Internal Control Module Knock Sensor 1 Processor Performance

P06B6 Internal Control Module Knock Sensor 1 Processor Performance

OBD-II DTC Datasheet

The performance of the processor 1 of the knock sensor of the internal control module

What does this mean?

This Generic Powertrain Diagnostic Trouble Code (DTC) is commonly applied to many OBD-II vehicles. This may include, but is not limited to, Chevrolet, Subaru, Ford, Mazda, BMW, Peugeot, etc.

When the P06B6 code persists, it means the powertrain control module (PCM) has detected an internal processor performance error with a specific knock sensor circuit (labeled 1). Other controllers may also detect an internal PCM performance error (with knock sensor circuit) and cause P06B6 to be stored.

The knock sensor is usually screwed directly into the cylinder block. This is a piezoelectric sensor. The location of the knock sensor will vary from manufacturer to manufacturer, but most are on the sides of the block (between the water jacket frost plugs) or in the depression under the intake manifold. Knock sensors located on the sides of the cylinder block are often screwed directly into the engine coolant passages. When the engine is warm and the engine cooling system is pressurized, removal of these sensors can cause severe burns from hot coolant. Allow engine to cool before removing any knock sensor and always dispose of coolant properly. 

The knock sensor is based on a piezoelectric sensitive crystal. When shaken or vibrated, the piezoelectric crystal creates a small voltage. Since the knock sensor control circuit is usually single wire, the voltage generated by the vibration is recognized by the PCM as engine noise or vibration. The vibration force that the piezoelectric crystal (inside the knock sensor) encounters determines the level of voltage created in the circuit.

If the PCM detects a knock sensor voltage level indicative of engine knock or severe spark knock; this can slow down the ignition timing and the knock sensor control code can be stored.

The knock sensor always generates a very low voltage when the engine is running. This is because slight vibration is inevitable, no matter how smoothly the engine runs.

The internal control module monitoring processors are responsible for the various controller self-testing functions and the overall accountability of the internal control module. Knock sensor inputs and outputs are self-tested and continuously monitored by the PCM and other relevant controllers. The transmission control module (TCM), traction control module (TCSM), and other controllers also interact with the knock sensor system.

Whenever the ignition is turned on and the PCM is energized, a self-test of the knock sensor system is triggered. In addition to performing a self test on the internal controller, the Controller Area Network (CAN) also compares the signals from each individual module to ensure that each controller is working as expected. These tests are performed at the same time.

If the PCM detects an internal mismatch in the knock sensor processor, a code P06B6 will be stored and a malfunction indicator lamp (MIL) may illuminate. In addition, if the PCM detects a problem between any of the on-board controllers that indicates an internal system error in the knock sensor, a P06B6 code will be stored and a malfunction indicator lamp (MIL) may illuminate. It may take several fail cycles to illuminate the MIL, depending on the perceived severity of the malfunction.

Example of PKM photo: P06B6 Internal Control Module Knock Sensor 1 Processor Performance

What is the severity of this DTC?

Internal control module processor codes are to be classified as Severe. A stored P06B6 code can cause various handling problems.

What are some of the symptoms of the code?

Symptoms of a P06B6 trouble code may include:

  • Loud engine noises
  • Reduced fuel efficiency
  • Various symptoms of engine drivability
  • Other Stored Diagnostic Trouble Codes

What are some of the common causes for the code?

Reasons for this code may include:

  • Bad PCM or PCM programming error
  • Defective knock sensor
  • Faulty knock sensor wiring and / or connectors
  • Faulty controller power relay or blown fuse
  • Open or short circuit in the circuit or connectors in the CAN harness
  • Insufficient grounding of the control module

What are some steps to troubleshoot the P06B6?

Even for the most experienced and well-equipped professional technician, diagnosing the P06B6 code can be challenging. There is also the problem of reprogramming. Without the necessary reprogramming equipment, it will be impossible to replace the faulty controller and carry out a successful repair.

If there are ECM / PCM power supply codes, they obviously need to be corrected before attempting to diagnose P06B6.

There are some preliminary tests that can be performed before declaring a controller as faulty. You will need a diagnostic scanner, a digital volt-ohmmeter (DVOM) and a source of reliable information about the vehicle.

Connect the scanner to the vehicle diagnostic port and get all stored codes and freeze frame data. You will want to write this information down just in case the code turns out to be intermittent. After recording all relevant information, clear the codes and test drive the vehicle until the code is cleared or the PCM enters ready mode. If the PCM enters ready mode, the code is intermittent and harder to diagnose. The condition that led to the persistence of P06B6 may even get worse before a diagnosis can be made. If the code is reset, continue with this short list of pre-tests.

When trying to diagnose P06B6, information can be your best tool. Search your vehicle information source for technical service bulletins (TSBs) that match the stored code, vehicle (year, make, model, and engine) and symptoms displayed. If you find the correct TSB, it can provide diagnostic information that will help you to a great extent.

Use your vehicle information source to obtain connector views, connector pinouts, component locators, wiring diagrams, and diagnostic block diagrams relevant to the code and vehicle in question.

Use the DVOM to test the fuses and relays of the controller power supply. Check and replace blown fuses if necessary. Fuses should be checked with a loaded circuit.

If all fuses and relays are working properly, a visual inspection of the wiring and harnesses associated with the controller should be performed. You will also want to check the chassis and motor ground connections. Use your vehicle information source to obtain grounding locations for associated circuits. Use DVOM to check ground integrity.

Visually inspect the system controllers for damage caused by water, heat, or collision. Any controller damaged, especially by water, is considered defective.

If the power and ground circuits of the controller are intact, suspect a faulty controller or a controller programming error. Replacing the controller will require reprogramming. In some cases, you can purchase reprogrammed controllers from the aftermarket. Other vehicles / controllers will require onboard reprogramming, which can only be done through a dealership or other qualified source.

  • Unlike most other codes, P06B6 is likely caused by a faulty controller or a controller programming error.
  • Check the system ground for continuity by connecting the negative test lead of the DVOM to ground and the positive test lead to the battery voltage.

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