P0845 moderate

Transmission Fluid Pressure Sensor/Switch B Circuit

The P0845 code means the vehicle's onboard diagnostic system has detected: Transmission Fluid Pressure Sensor/Switch B Circuit. This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: hard
Estimated cost: $150 - $600 (parts and labor)

Check Your Fluid First

ANCEL AD310 OBD-II Scanner

Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.

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Read Transmission Codes

LAUNCH CRP123X (Reads All Systems)

Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.

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Common Symptoms

Check Engine Light illuminated
Erratic shifting patterns
Transmission slipping in certain gears
Vehicle may enter limp mode

Probable Causes (Ranked by Likelihood)

Faulty transmission fluid pressure sensor B Very High
Wiring fault in pressure sensor B circuit High
Corroded connector at pressure sensor B Moderate
Internal valve body issue affecting B circuit pressure Low

Step-by-Step Diagnostic Procedure

Check transmission fluid level and condition
Monitor pressure sensor B data on a scan tool and compare to sensor A
Inspect wiring and connector at pressure sensor B for damage
Test sensor B resistance and compare to manufacturer specifications

Frequently Asked Questions

What is pressure sensor B vs sensor A?

Transmissions with multiple pressure sensors use A and B to monitor pressure at different points in the hydraulic circuit. Sensor B typically monitors a secondary pressure circuit or specific clutch pack pressure.

Can I drive with P0845?

You can drive short distances, but the transmission may not shift correctly. Prolonged driving can cause additional wear to internal components.

Are pressure sensors A and B interchangeable?

In some vehicles the sensors are the same part number, but they are located in different positions. Always verify the correct part number for each location.