P0846 - TRANSMISSION FLUID PRESSURE SENSOR / SWITCH "B" CIRCUIT RANGE / PERFORMANCE

The TPF (Transmission Fluid Pressure) sensor determines the internal pressure of the transmission. Besides, it turns the mechanical pressure of the transmission into an electrical signal, which is sent to the Transmission Control Module (TCM). This data is used to control the outputs of the pressure solenoids. The quality of the transmission shift is highly dependent on the signal from the TPF Sensor. Some transmissions may have multiple TPF Sensors depending on the manufacturer.

The Powertrain Control Module (PCM) delivers 5 volts of the reference voltage to the TPF Sensor, and the TPF Sensor changes its internal resistance based on line pressure, then sends a signal voltage back to the PCM. The DTC P0846 OBDII is set when the PCM detects a malfunction in the TPF Sensor circuit.

• The Check Engine light will turn on.
• Transmission shifts are hard.
• The transmission slips.
• The fail-safe mode is activated.

Reasons for setting the P0846 OBD2 fault code:

• The Transmission Fluid Pressure Sensor may be faulty.
• TPF Sensor circuit may have bad wiring.
• Perhaps the transmission has internal damage.

To troubleshoot the P0846 ODBII diagnostic code, follow the steps below:

• Check that the transmission fluid level and condition meet the requirements for proper system operation. If the fluid level is found to be below the required level, check for leaks. Repair as required.
• Check the Transmission Fluid Pressure Sensor wires and connectors, and make sure no damage would prevent proper operation in the circuit. Any fault wires or connectors should be repaired or replaced.
• Check that the resistance, ground, and return signal voltage values are the same as the manufacturer's specifications. Repair wiring as required.
• Use a multimeter and verify that the resistance of the TPF Sensor is within the manufacturer's recommended range. If the meter shows infinite resistance, replace the sensor.