Transmission Fluid Pressure Sensor Circuit Intermittent
The P0879 code indicates an intermittent fault in the transmission fluid pressure sensor or its circuit. This sensor monitors hydraulic pressure inside the transmission, and the powertrain control module (PCM) uses this data to control shift timing and line pressure. An intermittent signal can cause erratic shifting, slipping, or harsh engagement. Common causes include a faulty sensor, damaged wiring, loose connectors, or low transmission fluid. This issue should be addressed promptly to prevent transmission damage.
1. Symptoms You Will Notice
- Check Engine Light on
- Erratic or harsh shifting
- Transmission slipping or delayed engagement
- Transmission stuck in limp mode
2. Most Common Causes
- Faulty transmission fluid pressure sensor
- Damaged or corroded wiring/connectors
- Intermittent electrical connection
- Low or contaminated transmission fluid
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition.
Step 3: Visually check wiring and connectors for damage or corrosion.
Step 4: Test sensor resistance and voltage with a multimeter.
Step 5: Clear code and test drive to see if it returns.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as intermittent pressure readings can cause transmission damage. Limp mode may activate, limiting speed and drivability.
How much does it cost to fix?▼
Typical repair costs range from $50 to $150 for sensor replacement, plus diagnostic fees. Wiring repairs may add $100-$200.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.