Transmission Fluid Pressure Sensor/Switch Circuit High
The P0990 code indicates that the Powertrain Control Module (PCM) has detected a voltage signal from the transmission fluid pressure sensor that is higher than the expected range. This sensor monitors the hydraulic pressure inside the transmission to ensure proper shifting and operation. A high circuit condition typically means there is a short to voltage, a faulty sensor, or a wiring issue. This can lead to erratic shifting, transmission slippage, or even transmission damage if not addressed.
01. Most Common Causes
- Faulty transmission fluid pressure sensor
- Short to voltage in the sensor circuit
- Damaged wiring or connector
- Corroded terminals
- PCM failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slippage
- Delayed engagement
- Transmission stuck in limp mode
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional transmission codes.
Step 2: Visually inspect the transmission fluid pressure sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage and resistance with a multimeter; compare to manufacturer specifications.
Step 4: Check for shorts to voltage or ground in the sensor circuit.
Step 5: If all else is normal, replace the transmission fluid pressure sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause transmission damage. The vehicle may enter limp mode, limiting speed and drivability.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for the sensor and labor, but can be higher if wiring repairs or PCM replacement is needed.