P081B Starter Disable Circuit High

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P081B Starter Disable Circuit High

OBD-II Trouble Code Technical Description

Starter Disable Circuit High

What does that mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Subaru, BMW, Mazda, Volkswagen, Audi, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.

If your vehicle has stored a code P081B, it means that the powertrain control module (PCM) has detected a degree of voltage that is lower than expected in the starter disable switch circuit. This type of code may be applicable to vehicles with manual or automatic transmissions.

The starter disable switch is usually a single circuit, open/closed switch which interrupts voltage between the ignition switch and the starter solenoid if the clutch is not depressed, the transmission (manual) is not in neutral, or the transmission (automatic) is not in park. Vehicle applications with an automatic transmission may have the starter disable switch integrated into the neutral safety switch or shift selector switch. The transmission control module (TCM) or the PCM monitor starter disable circuit voltage with the ignition in the ON position. The TCM may be a stand alone module or part of the PCM.

If the PCM detects that starter disable switch circuit voltage is not within allowable parameters, a code P081B may be stored and a malfunction indicator lamp (MIL) illuminated. Multiple ignition cycles (with a failure) may be required for MIL illumination.

What is the severity of this DTC?

A stored code P081B could be accompanied by a no-start condition and also indicates that either an electrical issue or a mechanical failure has occurred. Conditions which contributed to a code of this nature being stored should be rectified as quickly as possible.

What are some of the symptoms of the code?

Symptoms of a P081B trouble code may include:

  • Engine will not start
  • Engine starts with the transmission in gear
  • No symptoms may be exhibited
  • What are some of the common causes of the code?

    Causes for this code may include:

  • Defective starter disable switch
  • Shorted or open wiring or connectors in starter disable switch circuit
  • Faulty PCM or a programming error
  • What are some P081B troubleshooting steps?

    A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle specific diagnostic information will be required to diagnose a code P081B.

    You may use your source of vehicle information to locate a technical service bulletin (TSB) that matches the vehicle year, make, and model; as well as the engine size, code/s stored, and symptoms exhibited. If you find one, it could yield helpful diagnostic information.

    Use the scanner (connected to the vehicle diagnostic connector) to retrieve all stored codes and pertinent freeze frame data. It is a good idea to write this information down before clearing the codes then test-drive the vehicle until the PCM either enters readiness mode or the code is reset.

    If the PCM enters readiness mode at this time, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions which contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

    If the code is immediately reset, the next step of your diagnosis will require that you search your vehicle information source for diagnostic flow-charts, connector pin-out charts, connector face views, and component testing procedures/specifications.

    Step 1

    Use the DVOM to test voltage, ground, and signal output at the appropriate starter disable switch. Typical starter disable switch circuits consist of either battery voltage (when activated) or ground (when deactivated).

    Step 2

    Use your source of vehicle diagnostic information and the DVOM to test starter disable switches as required. Replace switches that do not test within system parameters.

    Step 3

    If system switches and circuits are functional, use the DVOM to test starter disable switch circuits to the starter, as well as to the PCM. Disconnect all controllers prior to using the DVOM for testing.

  • Starter disable switch circuit codes are most often attributed to switch failure
  • Vehicles with manual transmissions often use multiple starter disable switches (one for the clutch and another for neutral)
  • Need help?

    Let us fix your problem. You are most welcome our diagnosis experts have in most cases the knowledge and skills to find the cause of the error code p081b and to solve the problems.

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    "Delete Error Code Permanently, Disable DTC Error Code Function for p081b in the ECU"

    In extreme cases, we even have the option to permanently remove the specific DTC p081b and disable the function of the specific error code in the ECU. All other fault code functions will then continue to work to protect the engine. This is different from clearing an error code with a diagnostic device. We have the option to permanently remove the function of the specific error code, so that it never comes back. Also emergency running that occurs on the specific error code can be solved in most cases.

    Of course we prefer to first try to solve the cause of the error code, but sometimes the only solution is to permanently disable the DTC function of p081b.

    Make an appointment for permanent removal of p081b