Transmission Fluid Pressure Sensor/Switch Circuit Intermittent
The P0879 code indicates an intermittent fault in the transmission fluid pressure sensor or switch circuit. This sensor monitors hydraulic pressure within the transmission to ensure proper shifting and torque converter operation. An intermittent signal can cause erratic transmission behavior, slipping, or harsh shifts. The issue may stem from a faulty sensor, damaged wiring, poor electrical connections, or internal transmission problems.
01. Most Common Causes
- Faulty transmission fluid pressure sensor
- Damaged or corroded wiring/connectors
- Intermittent electrical short or open circuit
- Low or contaminated transmission fluid
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Transmission stuck in limp mode
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition; top off or replace if necessary.
Step 3: Visually check wiring and connectors for damage, corrosion, or loose connections.
Step 4: Test the pressure sensor resistance and voltage with a multimeter per manufacturer specs.
Step 5: If wiring and sensor are OK, check for internal transmission issues (e.g., clogged passages).
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 lead to transmission damage or unsafe driving conditions. Have the vehicle inspected promptly.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Sensor replacement parts range from $30-$100, plus labor. Total repair can be $100-$300 depending on the cause.