Transmission Fluid Pressure Sensor/Switch Circuit Low
The P0877 code indicates that the Powertrain Control Module (PCM) has detected a low voltage signal from the transmission fluid pressure (TFP) sensor or switch circuit. This sensor monitors hydraulic pressure within the transmission to ensure proper shift timing and line pressure. A low circuit condition typically means the signal voltage is below the expected range (often below 0.5V), which can be caused by a faulty sensor, wiring issues, or internal transmission problems.
01. Most Common Causes
- Faulty transmission fluid pressure sensor
- Open or shorted wiring in the sensor circuit
- Corroded or damaged connector
- Low transmission fluid level or contamination
- Internal transmission mechanical failure
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping or delayed engagement
- Reduced fuel economy
- 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 the TFP sensor connector and wiring for damage, corrosion, or loose connections.
Step 4: Using a multimeter, test the sensor signal voltage at the PCM connector; compare to manufacturer specifications.
Step 5: If voltage is low, disconnect the sensor and check for continuity between the sensor ground and signal circuits; repair as needed.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with P0877 as it can cause transmission damage due to improper line pressure. Limp mode may limit speed and damage components.
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.