📌 Meaning of Code P0846
The code P0846 indicates a malfunction in the electrical circuit of the Transmission Fluid Pressure Sensor “B” (TFPS).
This sensor measures the internal transmission pressure and sends the data to the PCM (Powertrain Control Module) or the TCM (Transmission Control Module).
If the sensor’s voltage does not match the expected values, the code is recorded.
⚠️ Severity of the Code
Severity: moderate to high
The vehicle may enter limp mode (starting in 2nd or 3rd gear) to protect the transmission.
Abnormal gear shifts or loss of performance may occur. Prompt repair is recommended.
🔍 Possible Symptoms
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Check Engine light on
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Harsh or irregular gear shifts
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Vehicle starting in 2nd or 3rd gear (limp mode)
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Transmission stuck in one gear
❗ Possible Causes
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Faulty TFPS sensor (most common)
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Damaged wires: cut, shorted to ground or power
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Corroded or dirty connectors
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Internal mechanical issue (low fluid pressure, stuck valve, leak)
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Faulty PCM (rare)
🛠️ Diagnostic and Repair Steps
✅ Step 1: Check Technical Service Bulletins (TSB)
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The issue may be known by the manufacturer with a documented solution
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Look for any TSBs related to code P0846 for your model
✅ Step 2: Visually inspect the sensor and its wiring
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The TFPS sensor is usually located on or in the transmission valve body
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Check the condition of wires, connectors, and insulation (signs of burning, corrosion, melted plastic)
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Clean connectors with electrical contact cleaner and a soft brush if needed
✅ Step 3: Clear codes and test
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Use an OBD-II diagnostic tool to clear the codes
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Restart the engine and observe if the code returns
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If the code disappears: the problem was likely with the connections
✅ Step 4: Electrically test the TFPS sensor
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Use a digital multimeter (DVOM):
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Key in OFF position, disconnect the sensor
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Test continuity and voltages between the harness wires (ground, signal, power)
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Compare values to manufacturer specifications
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✅ Step 5: Replace the sensor if necessary
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If electrical tests show the sensor is out of specifications, replace it
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Reset codes and test again
📌 Related Codes to Monitor
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P0845 – Pressure Sensor Circuit “B”
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P0847 – Low Pressure
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P0848 – High Pressure
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P0849 – Intermittent Signal