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P0845 OBD-II Trouble Code: Transmission Fluid Pressure Sensor/Switch B Circuit

Check Engine Light

P0845 code definition

The P0845 code is detected with an abnormal voltage reading from the transmission fluid pressure sensor circuit alerts the PCM. This code is often stored with other torque converter clutch, shift solenoid, transmission slippage, gear ratio, or lock up codes.

What the P0845 code means

In order to determine the right amount of pressure for transmission operation, several sensors and readings are utilized by the PCM. If the right amount of fluid pressure is not detected from the fluid pressure sensor, it means that the right amount of transmission pressure cannot be achieved. This detection will cause the PCM to store the P0845 code.

What causes the P0845 code?

Typically, the P0845 code is caused by a faulty electronic pressure control solenoid. However, a faulty transmission fluid sensor may also be to blame. Other causes include:

  • Blocked transmission fluid passages
  • Internal transmission failures
  • Low transmission fluid
  • Contaminated or dirty transmission fluid
  • A faulty PCM or TCM, in very rare cases

What are the symptoms of the P0845 code?

Before the P0845 code is detected, the vehicle’s owner may notice harsh shifting, a slipping transmission, an overheated transmission, decreased fuel efficiency, or a complete failure to engage or disengage from the torque converter clutch. The Check Engine light should also be illuminated.

How does a mechanic diagnose the P0845 code?

In order to diagnose the P0845 code, the mechanic should begin by verifying the code with an OBD-II scanner. Any issues with transmission components should always be addressed first with an inspection of the transmission fluid. If the fluid is low, it should be filled; if it is dirty or smells burnt, the system may need to be flushed and be refilled with clean transmission fluid.

After this step, the mechanic should clear the code and retest the system. If the code reappears, they will need to continue on with other diagnostic procedures, beginning with a check of all electrical components. After each potential repair is attempted, the code should be cleared and the system should be rechecked, to ensure that the right fix is narrowed down.

Common mistakes when diagnosing the P0845 code

It is common for the high pressure pump to be replaced, when in fact the transmission pressure sensor itself, or the electronic pressure control solenoid or other wiring malfunctions were to blame. It’s important that all electrical components be checked before replacing any major parts, as shorted connections are frequently the issue.

How serious is the P0845 code?

The P0845 code is considered very serious, and its presence indicates an issue that should be addressed right away. If this issue is not resolved as soon as the code is detected, it could lead to a vehicle that is not operational, or that is unsafe.

What repairs can fix the P0845 code?

There are many ways that a technician can address a P0845 code detection. They include:

  • Replace a faulty electronic pressure control solenoid.
  • Replace a faulty transmission fluid sensor
  • Cleaning blocked transmission fluid passages.
  • Addressing any internal transmission failures.
  • Refilling low transmission fluid.
  • Flushing the system of contaminated or dirty transmission fluid, and replacing it with clean fluid.
  • Replacing a faulty PCM or TCM, in very rare cases.

Need help with a P0845 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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