Transmission Fluid Pressure Sensor/Switch "F" Circuit High
Diagnostic trouble code P0995 indicates that the transmission control module has detected an abnormally high voltage signal from the transmission fluid pressure sensor/switch 'F' circuit. This high voltage condition typically points to an open circuit, a short to power, or a failed sensor, preventing the computer from accurately regulating transmission line pressure.
This code requires immediate attention as driving with unregulated transmission fluid pressure can cause severe internal transmission damage or force the vehicle into limp mode.
Common symptoms
- Illuminated Check Engine Light
- Harsh or erratic transmission shifting
- Transmission slipping during acceleration
- Vehicle stuck in limp mode (restricted to a single gear)
- Failure to engage overdrive or specific gears
Likely causes
- Defective transmission fluid pressure sensor/switch 'F'
- Broken, frayed, or damaged wiring in the sensor circuit causing an open
- Corroded, loose, or contaminated electrical connector at the sensor
- Short to power in the sensor signal circuit
- Faulty Transmission Control Module (TCM) or PCM (rare)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Ensure the fluid is at the correct level and not burnt or heavily contaminated, as poor fluid can exacerbate pressure issues, though this code primarily indicates an electrical fault.
Visually inspect the wiring harness and connector for sensor 'F'.
Look for: Look for broken wires, melted insulation, pushed-out pins, or corrosion that could cause an open circuit or short to power.
Test the sensor circuit for reference voltage and ground.
Look for: Verify a steady 5-volt reference (or manufacturer specific voltage) and a good ground at the connector; a missing ground can cause the signal to read high.
Measure the internal resistance of the transmission fluid pressure sensor 'F'.
Look for: Compare the resistance values to the manufacturer's specifications; an open circuit (infinite resistance) confirms the sensor has failed internally.
Check for a short to voltage on the signal wire.
Look for: With the sensor and module disconnected, check for voltage on the signal wire; any voltage indicates a short to another power source in the harness.
This page explains the generic P0995 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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