What Does P0994 Mean?
The TCM has detected that the transmission fluid pressure sensor/switch 'F' circuit is reading abnormally low voltage. This sensor monitors hydraulic pressure in a specific transmission clutch pack or fluid circuit. A low reading typically indicates a short to ground, failed sensor, or actual low fluid pressure condition that could compromise shift quality.
Common Causes
35%
Faulty transmission fluid pressure sensor/switch F with internal short to ground
25%
Wiring harness short to ground or damaged insulation in sensor F circuit
25%
Low transmission fluid level or degraded fluid causing actual low pressure
15%
TCM internal circuit failure or corroded connector at TCM
Diagnostic Steps
1
Step 1: Check transmission fluid level and condition with engine running at operating temperature. Fluid should be pink/red and at the correct level on the dipstick. Dark, burnt-smelling fluid indicates internal damage.
2
Step 2: Access the pressure sensor F connector at the transmission case. Inspect for corrosion, bent pins, moisture intrusion, or damaged seals. Clean contacts with electrical contact cleaner.
3
Step 3: With the connector unplugged, measure resistance across the sensor terminals using a DVOM. Compare to manufacturer specs (typically 30-100 ohms at zero pressure). An open or very low reading indicates a failed sensor.
4
Step 4: Backprobe the sensor signal wire at the TCM connector. With KOEO, verify 5V reference is present. If reference is missing, trace wiring for shorts to ground using a wiring diagram.
5
Step 5: If wiring and sensor test good, install a known-good pressure sensor and verify the pressure PID reads within specification using live data (typically 0-300 PSI depending on gear and load).
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The TCM has detected that the transmission fluid pressure sensor/switch 'F' circuit is reading abnormally low voltage. This sensor monitors hydraulic pressure in a specific transmission clutch pack or fluid circuit. A low reading typically indicates a short to ground, failed sensor, or actual low fl...
The most common cause of P0994 (Transmission Fluid Pressure Sensor/Switch "F" Circuit Low) is: Faulty transmission fluid pressure sensor/switch F with internal short to ground
Typical repair costs for P0994 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may exhibit harsh or delayed shifts, and transmission damage can occur if driven extensively. Reduce driving and have repaired promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0994 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Hydraulic Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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