Transmission Fluid Pressure Sensor/Switch Circuit High
The P0990 code indicates that the Transmission Control Module (TCM) has detected a voltage signal from the transmission fluid pressure sensor that is higher than the expected range. This sensor monitors hydraulic pressure within the transmission to ensure proper shifting. A high circuit condition typically means there is a short to voltage, a faulty sensor, or an internal transmission issue causing excessive pressure.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping
- Vehicle may enter limp mode
2. Most Common Causes
- Faulty transmission fluid pressure sensor
- Short to voltage in the sensor circuit
- Damaged wiring or connector
- Internal transmission problem (e.g., stuck pressure regulator valve)
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Visually inspect the transmission fluid pressure sensor and its wiring 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 power or ground in the sensor circuit.
Step 5: If sensor and wiring are okay, perform a transmission pressure test to rule out internal issues.
4. 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 or unsafe driving conditions due to erratic shifting.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, but internal transmission repairs can be much higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.