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P0846 OBD-II Trouble Code: Transmission Fluid Pressure Sensor/Switch "B" Circuit Range/Performance

check engine light

P0846 code definition

The P0846 refers to a detected malfunction relating to the vehicle's transmission fluid pressure sensor circuit.

What the P0846 code means

The P0846 trouble code indicates that the Powertrain Control Module (PCM) has detected an anomalous fluid reading from the transmission system. The transmission system uses hydraulic fluid to regulate features like torque converter lockup and gearshift actuation. If the sensor circuit sends a fluid pressure reading to the PCM that falls outside manufacturer specifications, the P0846 trouble code will be stored.

What causes the P0846 code?

The cause of a P0846 trouble code may lie with a faulty component relating to the transmission, most commonly the faulty electronic pressure control solenoid or transmission fluid pressure sensor itself. Low, decontaminated or dirty transmission fluid may be to blame as well.

What are the symptoms of the P0846 code?

At its worst, the P0846 will disable the transmission and torque converter clutch. his will render the vehicle inoperable. Most instances, however, are less severe, usually resulting in harsh shifting and shift slippage, overheating transmission and lowered fuel efficiency. The vehicle's onboard computer will store a P0846 trouble code and signal the trouble lamp on the car's dashboard.

How does a mechanic diagnose the P0846 code?

A P0846 code can be first identified by using an ODB-II code reader. The transmission fluid pressure sensor circuit should be inspected thoroughly for apparent issues. Any related wiring should be checked in case there are issues with disconnected, corroded or faulty circuits. The transmission fluid itself should be checked for signs of issue, both visually and with use of a dipstick. Contaminated, burned, dirty or otherwise problematic transmission fluid may be a sign of other issues with the transmission system.

Common mistakes when diagnosing the P0846 code

Mechanics report that the wiring, circuitry, hydraulic blockages, transmission fluid, and transmission fluid pressure sensor itself are overlooked in favour of the transmission's pressure pumps.

How serious is the P0846 code?

In the worst instances, the vehicle will be rendered inoperable by a P0846 code. Moderate cases may negatively affect the vehicle's drivability. In any case, a P0846 trouble code is a potentially serious issue, and should be addressed as soon as possible.

What repairs can fix the P0846 code?

Any faulty, damaged or disconnected circuits and connectors should be repaired or replaced. Burned, dirty or contaminated transmission fluid will need to be replaced. If there is a shortage of transmission fluid, it should be topped up accordingly. In rare instances where the PCM itself is faulty, it will need to be replaced and the related modules reprogrammed as needed. This should be saved as a last ditch option however, as the process is costly and time-consuming.

Additional comments for consideration regarding the P0846 code

If the trouble code returns and the transmission system has been fixed, check the voltage and suspect an electrical circuit problem. Other trouble codes related to the torque converter clutch and transmission system often come alongside a P0846 code.

Need help with a P0846 code?

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