P2784: Input/Turbine Speed Sensor Correlation
The P2784 code indicates that the powertrain control module (PCM) has detected a correlation error between the input (turbine) speed sensor and the output speed sensor. This typically means the transmission is slipping or the sensors are providing inconsistent data, which can lead to harsh shifting, delayed engagement, or loss of power. The issue is often related to low transmission fluid, a faulty sensor, or internal transmission wear.
01. Most Common Causes
- Low or contaminated transmission fluid
- Faulty input/turbine speed sensor
- Wiring or connector issues in the sensor circuit
- Internal transmission mechanical failure (e.g., worn clutches, torque converter issues)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or erratic shifting
- Transmission slipping or delayed engagement
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect transmission fluid level and condition; top up or replace if necessary.
Step 3: Visually inspect the input speed sensor and its wiring for damage or corrosion.
Step 4: Test the sensor resistance and compare to manufacturer specifications.
Step 5: Check for continuity and shorts in the sensor circuit between the sensor and PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the transmission may slip or fail, potentially causing further damage. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost varies: sensor replacement typically ranges from $50 to $150 for parts and labor. If internal transmission repair is needed, costs can exceed $1,000.